diff --git a/lib/symbols b/lib/symbols
index e32f50dfc9..5604a79340 100644
--- a/lib/symbols
+++ b/lib/symbols
@@ -90,6 +90,9 @@ texttt            font        textmode
 textup            font        textmode
 emph              font        textmode
 noun              font        textmode
+# ce and cf are provided by the mhchem package
+ce                font        forcetext
+cf                font        forcetext
 
 # old-style font commands
 bf                oldfont     none
diff --git a/src/Cursor.cpp b/src/Cursor.cpp
index dc20944178..911331861d 100644
--- a/src/Cursor.cpp
+++ b/src/Cursor.cpp
@@ -404,7 +404,10 @@ int Cursor::currentMode()
 	LASSERT(!empty(), /**/);
 	for (int i = depth() - 1; i >= 0; --i) {
 		int res = operator[](i).inset().currentMode();
-		if (res != Inset::UNDECIDED_MODE)
+		bool locked_mode = operator[](i).inset().lockedMode();
+		// Also return UNDECIDED_MODE when the mode is locked,
+		// as in this case it is treated the same as TEXT_MODE
+		if (res != Inset::UNDECIDED_MODE || locked_mode)
 			return res;
 	}
 	return Inset::TEXT_MODE;
diff --git a/src/LaTeXFeatures.cpp b/src/LaTeXFeatures.cpp
index 8f8e8b141d..aaf5460b0d 100644
--- a/src/LaTeXFeatures.cpp
+++ b/src/LaTeXFeatures.cpp
@@ -690,6 +690,10 @@ string const LaTeXFeatures::getPackages() const
 		packages << "\\PassOptionsToPackage{normalem}{ulem}\n"
 			    "\\usepackage{ulem}\n";
 
+	if (mustProvide("mhchem"))
+		packages << "\\PassOptionsToPackage{version=3}{mhchem}\n"
+			    "\\usepackage{mhchem}\n";
+
 	if (mustProvide("nomencl")) {
 		// Make it work with the new and old version of the package,
 		// but don't use the compatibility option since it is
diff --git a/src/insets/Inset.h b/src/insets/Inset.h
index ea8fbfc54a..e82657ef3b 100644
--- a/src/insets/Inset.h
+++ b/src/insets/Inset.h
@@ -470,6 +470,8 @@ public:
 	enum mode_type {UNDECIDED_MODE, TEXT_MODE, MATH_MODE};
 	/// return text or mathmode if that is possible to determine
 	virtual mode_type currentMode() const { return UNDECIDED_MODE; }
+	/// returns whether changing mode during latex export is forbidden
+	virtual bool lockedMode() const { return false; }
 	/// returns whether this inset is allowed in other insets of given mode
 	virtual bool allowedIn(mode_type) const { return true; }
 	/**
diff --git a/src/mathed/InsetMath.h b/src/mathed/InsetMath.h
index 589f7b27e3..4e79e7b6e4 100644
--- a/src/mathed/InsetMath.h
+++ b/src/mathed/InsetMath.h
@@ -97,6 +97,9 @@ public:
 	/// this is overridden in math text insets (i.e. mbox)
 	bool inMathed() const { return true; }
 
+	/// this is overridden by specific insets
+	virtual mode_type currentMode() const { return MATH_MODE; }
+
 	/// the ascent of the inset above the baseline
 	/// compute the size of the object for text based drawing
 	virtual void metricsT(TextMetricsInfo const & mi, Dimension & dim) const;
diff --git a/src/mathed/InsetMathFont.cpp b/src/mathed/InsetMathFont.cpp
index 86582600b8..dcf4747c60 100644
--- a/src/mathed/InsetMathFont.cpp
+++ b/src/mathed/InsetMathFont.cpp
@@ -44,6 +44,14 @@ InsetMath::mode_type InsetMathFont::currentMode() const
 }
 
 
+bool InsetMathFont::lockedMode() const
+{
+	if (key_->extra == "forcetext")
+		return true;
+	return false;
+}
+
+
 void InsetMathFont::metrics(MetricsInfo & mi, Dimension & dim) const
 {
 	FontSetChanger dummy(mi.base, key_->name);
@@ -93,6 +101,8 @@ void InsetMathFont::validate(LaTeXFeatures & features) const
 		features.require("amstext");
 	if (key_->name == "textipa")
 		features.require("tipa");
+	if (key_->name == "ce" || key_->name == "cf")
+		features.require("mhchem");
 }
 
 
diff --git a/src/mathed/InsetMathFont.h b/src/mathed/InsetMathFont.h
index a55c1f77b1..d93286dfae 100644
--- a/src/mathed/InsetMathFont.h
+++ b/src/mathed/InsetMathFont.h
@@ -31,6 +31,8 @@ public:
 	InsetMathFont const * asFontInset() const { return this; }
 	/// are we in math mode, text mode, or unsure?
 	mode_type currentMode() const;
+	/// do we allow changing mode during latex export?
+	bool lockedMode() const;
 	///
 	docstring name() const;
 	///
diff --git a/src/mathed/InsetMathGrid.cpp b/src/mathed/InsetMathGrid.cpp
index a6f19b5bea..fb90a3e3c8 100644
--- a/src/mathed/InsetMathGrid.cpp
+++ b/src/mathed/InsetMathGrid.cpp
@@ -1251,7 +1251,7 @@ void InsetMathGrid::doDispatch(Cursor & cur, FuncRequest & cmd)
 		parseflg |= Parse::VERBATIM;
 		// fall through
 	case LFUN_PASTE: {
-		if (cur.currentMode() == TEXT_MODE)
+		if (cur.currentMode() <= TEXT_MODE)
 			parseflg |= Parse::TEXTMODE;
 		cur.message(_("Paste"));
 		cap::replaceSelection(cur);
diff --git a/src/mathed/InsetMathNest.cpp b/src/mathed/InsetMathNest.cpp
index 1671452209..74d227394e 100644
--- a/src/mathed/InsetMathNest.cpp
+++ b/src/mathed/InsetMathNest.cpp
@@ -339,7 +339,7 @@ MathData InsetMathNest::glue() const
 
 void InsetMathNest::write(WriteStream & os) const
 {
-	ModeSpecifier specifier(os, currentMode());
+	ModeSpecifier specifier(os, currentMode(), lockedMode());
 	docstring const latex_name = name();
 	os << '\\' << latex_name;
 	for (size_t i = 0; i < nargs(); ++i)
@@ -524,7 +524,7 @@ void InsetMathNest::doDispatch(Cursor & cur, FuncRequest & cmd)
 		parseflg |= Parse::VERBATIM;
 		// fall through
 	case LFUN_PASTE: {
-		if (cur.currentMode() == TEXT_MODE)
+		if (cur.currentMode() <= TEXT_MODE)
 			parseflg |= Parse::TEXTMODE;
 		cur.recordUndoSelection();
 		cur.message(_("Paste"));
@@ -890,37 +890,37 @@ void InsetMathNest::doDispatch(Cursor & cur, FuncRequest & cmd)
 		break;
 
 	case LFUN_FONT_BOLD:
-		if (currentMode() == TEXT_MODE)
+		if (currentMode() <= TEXT_MODE)
 			handleFont(cur, cmd.argument(), "textbf");
 		else
 			handleFont(cur, cmd.argument(), "mathbf");
 		break;
 	case LFUN_FONT_BOLDSYMBOL:
-		if (currentMode() == TEXT_MODE)
+		if (currentMode() <= TEXT_MODE)
 			handleFont(cur, cmd.argument(), "textbf");
 		else
 			handleFont(cur, cmd.argument(), "boldsymbol");
 		break;
 	case LFUN_FONT_SANS:
-		if (currentMode() == TEXT_MODE)
+		if (currentMode() <= TEXT_MODE)
 			handleFont(cur, cmd.argument(), "textsf");
 		else
 			handleFont(cur, cmd.argument(), "mathsf");
 		break;
 	case LFUN_FONT_EMPH:
-		if (currentMode() == TEXT_MODE)
+		if (currentMode() <= TEXT_MODE)
 			handleFont(cur, cmd.argument(), "emph");
 		else
 			handleFont(cur, cmd.argument(), "mathcal");
 		break;
 	case LFUN_FONT_ROMAN:
-		if (currentMode() == TEXT_MODE)
+		if (currentMode() <= TEXT_MODE)
 			handleFont(cur, cmd.argument(), "textrm");
 		else
 			handleFont(cur, cmd.argument(), "mathrm");
 		break;
 	case LFUN_FONT_TYPEWRITER:
-		if (currentMode() == TEXT_MODE)
+		if (currentMode() <= TEXT_MODE)
 			handleFont(cur, cmd.argument(), "texttt");
 		else
 			handleFont(cur, cmd.argument(), "mathtt");
@@ -929,13 +929,13 @@ void InsetMathNest::doDispatch(Cursor & cur, FuncRequest & cmd)
 		handleFont(cur, cmd.argument(), "mathfrak");
 		break;
 	case LFUN_FONT_ITAL:
-		if (currentMode() == TEXT_MODE)
+		if (currentMode() <= TEXT_MODE)
 			handleFont(cur, cmd.argument(), "textit");
 		else
 			handleFont(cur, cmd.argument(), "mathit");
 		break;
 	case LFUN_FONT_NOUN:
-		if (currentMode() == TEXT_MODE)
+		if (currentMode() <= TEXT_MODE)
 			// FIXME: should be "noun"
 			handleFont(cur, cmd.argument(), "textsc");
 		else
@@ -955,7 +955,7 @@ void InsetMathNest::doDispatch(Cursor & cur, FuncRequest & cmd)
 		docstring const save_selection = grabAndEraseSelection(cur);
 		selClearOrDel(cur);
 		//cur.plainInsert(MathAtom(new InsetMathMBox(cur.bv())));
-		if (currentMode() == Inset::TEXT_MODE)
+		if (currentMode() <= Inset::TEXT_MODE)
 			cur.plainInsert(MathAtom(new InsetMathEnsureMath));
 		else
 			cur.plainInsert(MathAtom(new InsetMathBox(from_ascii("mbox"))));
@@ -1459,7 +1459,7 @@ bool InsetMathNest::interpretChar(Cursor & cur, char_type c)
 			// remove the '\\'
 			if (c == '\\') {
 				cur.backspace();
-				if (currentMode() == InsetMath::TEXT_MODE)
+				if (currentMode() <= InsetMath::TEXT_MODE)
 					cur.niceInsert(createInsetMath("textbackslash"));
 				else
 					cur.niceInsert(createInsetMath("backslash"));
@@ -1551,14 +1551,14 @@ bool InsetMathNest::interpretChar(Cursor & cur, char_type c)
 	selClearOrDel(cur);
 
 	if (c == '\n') {
-		if (currentMode() == InsetMath::TEXT_MODE)
+		if (currentMode() <= InsetMath::TEXT_MODE)
 			cur.insert(c);
 		return true;
 	}
 
 	if (c == ' ') {
-		if (currentMode() == InsetMath::TEXT_MODE) {
-			// insert spaces in text mode,
+		if (currentMode() <= InsetMath::TEXT_MODE) {
+			// insert spaces in text or undecided mode,
 			// but suppress direct insertion of two spaces in a row
 			// the still allows typing  '<space>a<space>' and deleting the 'a', but
 			// it is better than nothing...
@@ -1609,7 +1609,7 @@ bool InsetMathNest::interpretChar(Cursor & cur, char_type c)
 			cur.niceInsert(createInsetMath("sim"));
 			return true;
 		}
-		if (!isAsciiOrMathAlpha(c)) {
+		if (currentMode() == InsetMath::MATH_MODE && !isAsciiOrMathAlpha(c)) {
 			MathAtom at = createInsetMath("text");
 			at.nucleus()->cell(0).push_back(MathAtom(new InsetMathChar(c)));
 			cur.niceInsert(at);
diff --git a/src/mathed/InsetMathString.cpp b/src/mathed/InsetMathString.cpp
index 0dd17fe6d1..6e4c99ee70 100644
--- a/src/mathed/InsetMathString.cpp
+++ b/src/mathed/InsetMathString.cpp
@@ -103,7 +103,7 @@ void InsetMathString::mathmlize(MathStream & os) const
 
 void InsetMathString::write(WriteStream & os) const
 {
-	if (!os.latex()) {
+	if (!os.latex() || os.lockedMode()) {
 		os << str_;
 		return;
 	}
diff --git a/src/mathed/MathFactory.cpp b/src/mathed/MathFactory.cpp
index 006453410a..b27739270f 100644
--- a/src/mathed/MathFactory.cpp
+++ b/src/mathed/MathFactory.cpp
@@ -275,7 +275,7 @@ bool ensureMath(WriteStream & os, bool needs_math_mode, bool macro)
 }
 
 
-bool ensureMode(WriteStream & os, InsetMath::mode_type mode)
+int ensureMode(WriteStream & os, InsetMath::mode_type mode, bool locked)
 {
 	bool textmode = mode == InsetMath::TEXT_MODE;
 	if (os.latex() && textmode && os.pendingBrace()) {
@@ -284,9 +284,11 @@ bool ensureMode(WriteStream & os, InsetMath::mode_type mode)
 		os.pendingSpace(false);
 		os.textMode(true);
 	}
-	bool oldmode = os.textMode();
+	int oldmodes = os.textMode() ? 1 : 0;
 	os.textMode(textmode);
-	return oldmode;
+	oldmodes |= os.lockedMode() ? 2 : 0;
+	os.lockedMode(locked);
+	return oldmodes;
 }
 
 
diff --git a/src/mathed/MathStream.cpp b/src/mathed/MathStream.cpp
index 67622ebd54..d2a86af506 100644
--- a/src/mathed/MathStream.cpp
+++ b/src/mathed/MathStream.cpp
@@ -155,6 +155,12 @@ void WriteStream::textMode(bool textmode)
 }
 
 
+void WriteStream::lockedMode(bool locked)
+{
+	locked_ = locked;
+}
+
+
 WriteStream & operator<<(WriteStream & ws, MathAtom const & at)
 {
 	at->write(ws);
diff --git a/src/mathed/MathStream.h b/src/mathed/MathStream.h
index e88f7cd85e..2ab8f7f713 100644
--- a/src/mathed/MathStream.h
+++ b/src/mathed/MathStream.h
@@ -65,6 +65,10 @@ public:
 	void textMode(bool textmode);
 	/// tell whether we are in text mode or not when producing latex code
 	bool textMode() const { return textmode_; }
+	/// tell whether we are allowed to switch mode when producing latex code
+	void lockedMode(bool locked);
+	/// tell whether we are allowed to switch mode when producing latex code
+	bool lockedMode() const { return locked_; }
 	/// LaTeX encoding
 	Encoding const * encoding() const { return encoding_; }
 private:
@@ -84,6 +88,8 @@ private:
 	bool pendingbrace_;
 	/// are we in text mode when producing latex code?
 	bool textmode_;
+	/// are we allowed to switch mode when producing latex code?
+	bool locked_;
 	///
 	int line_;
 	///
@@ -109,7 +115,7 @@ WriteStream & operator<<(WriteStream &, unsigned int);
 bool ensureMath(WriteStream & os, bool needs_math_mode = true, bool macro = false);
 
 /// ensure the requested mode, possibly by closing \ensuremath
-bool ensureMode(WriteStream & os, InsetMath::mode_type mode);
+int ensureMode(WriteStream & os, InsetMath::mode_type mode, bool locked);
 
 
 /**
@@ -169,12 +175,22 @@ private:
  * environment works in a given mode. For example, \mbox works in text
  * mode, but \boxed works in math mode. Note that no mode changing commands
  * are needed, but we have to track the current mode, hence this class.
+ * This is only used when exporting to latex and helps determining whether
+ * the mode needs being temporarily switched when a command would not work
+ * in the current mode. As there are cases where this switching is to be
+ * avoided, the optional third parameter can be used to lock the mode.
  *
- * Example:
+ * Example 1:
  *
  *      ModeSpecifier specifier(os, TEXT_MODE);
  *
- * Sets the current mode to text mode.
+ * Sets the current mode to text mode and allows mode switching.
+ *
+ * Example 2:
+ *
+ *      ModeSpecifier specifier(os, TEXT_MODE, true);
+ *
+ * Sets the current mode to text mode and disallows mode switching.
  *
  * At the end of specifier's scope the mode is reset to its previous value.
  */
@@ -182,15 +198,20 @@ class ModeSpecifier
 {
 public:
 	///
-	explicit ModeSpecifier(WriteStream & os, InsetMath::mode_type mode)
-		: os_(os), textmode_(ensureMode(os, mode)) {}
+	explicit ModeSpecifier(WriteStream & os, InsetMath::mode_type mode,
+				bool locked = false)
+		: os_(os), oldmodes_(ensureMode(os, mode, locked)) {}
 	///
-	~ModeSpecifier() { os_.textMode(textmode_); }
+	~ModeSpecifier()
+	{
+		os_.textMode(oldmodes_ & 1);
+		os_.lockedMode(oldmodes_ & 2);
+	}
 private:
 	///
 	WriteStream & os_;
 	///
-	bool textmode_;
+	int oldmodes_;
 };
 
 
diff --git a/src/mathed/MathSupport.cpp b/src/mathed/MathSupport.cpp
index 267e7ea1af..528a25e1de 100644
--- a/src/mathed/MathSupport.cpp
+++ b/src/mathed/MathSupport.cpp
@@ -580,6 +580,12 @@ fontinfo fontinfos[] = {
 	{"textipa",       inh_family, inh_series,
 			  inh_shape, Color_foreground},
 
+	// mhchem support
+	{"ce",            inh_family, inh_series,
+			  inh_shape, Color_foreground},
+	{"cf",            inh_family, inh_series,
+			  inh_shape, Color_foreground},
+
 	// LyX internal usage
 	{"lyxtex",        inh_family, inh_series,
 			  UP_SHAPE, Color_latex},
diff --git a/status.16x b/status.16x
index 1209629faf..8d9a66e8b8 100644
--- a/status.16x
+++ b/status.16x
@@ -179,6 +179,9 @@ What's new
 
 - Fix wrong labeling as "child only" branch if branches were unknown.
 
+- Fix typesetting of chemical equations by adding support for the mhchem
+  package (bugs 6047, 4043, and 5394).
+
 
 * DOCUMENTATION AND LOCALIZATION