diff --git a/interfaces/matlab/toolbox/@Reactor/setChemistry.m b/interfaces/matlab/toolbox/@Reactor/setChemistry.m
new file mode 100644
index 000000000..3fb14062e
--- /dev/null
+++ b/interfaces/matlab/toolbox/@Reactor/setChemistry.m
@@ -0,0 +1,29 @@
+function setChemistry(r, flag)
+% SETCHEMISTRY  Enable or disable changing reactor composition by reactions.
+% setChemistry(r, flag)
+% If the chemistry is disabled, then the reactor composition is
+% constant. The parameter should be the string ``'on'`` to enable the
+% species equations, or ``'off'`` to disable it.
+%
+% By default, Reactor objects are created with the species equations
+% enabled if there are reactions present in the mechanism file, and
+% disabled otherwise. ::
+%
+%     >> setChemistry(r, 'on');
+%     >> setChemistry(r, 'off');
+%
+% :param r:
+%     Instance of class :mat:func:`Reactor`
+% :param flag:
+%     String, either ``'on'`` or ``'off'`` to enable and disable
+%     solving the energy equation, respectively
+%
+
+if strcmp(flag, {'on'})
+    iflag = true;
+elseif strcmp(flag, {'off'})
+    iflag = false;
+else
+    error('Input to setChemistry not understood. It must be either "on" or "off".');
+end
+reactormethods(8, r.index, iflag);
diff --git a/interfaces/matlab/toolbox/@Reactor/setEnergy.m b/interfaces/matlab/toolbox/@Reactor/setEnergy.m
index 80ef46849..71d71675b 100644
--- a/interfaces/matlab/toolbox/@Reactor/setEnergy.m
+++ b/interfaces/matlab/toolbox/@Reactor/setEnergy.m
@@ -15,7 +15,7 @@ function setEnergy(r, flag)
 % :param r:
 %     Instance of class :mat:func:`Reactor`
 % :param flag:
-%     String, either ``'on'`` or ``'off`` to enable and disable
+%     String, either ``'on'`` or ``'off'`` to enable and disable
 %     solving the energy equation, respectively
 %
 
diff --git a/src/clib/ctreactor.cpp b/src/clib/ctreactor.cpp
index 6937fad79..f97f92392 100644
--- a/src/clib/ctreactor.cpp
+++ b/src/clib/ctreactor.cpp
@@ -169,6 +169,19 @@ extern "C" {
         }
     }
 
+    int reactor_setChemistry(int i, bool cflag)
+    {
+        try {
+            // @todo This should not fail silently
+            if (ReactorCabinet::item(i).type() >= ReactorType) {
+                ReactorCabinet::get<Reactor>(i).setChemistry(cflag);
+            }
+            return 0;
+        } catch (...) {
+            return handleAllExceptions(-1, ERR);
+        }
+    }
+
     int reactor_setEnergy(int i, int eflag)
     {
         try {
diff --git a/src/clib/ctreactor.h b/src/clib/ctreactor.h
index e8733f21f..06eb9178b 100644
--- a/src/clib/ctreactor.h
+++ b/src/clib/ctreactor.h
@@ -11,6 +11,7 @@ extern "C" {
     CANTERA_CAPI int reactor_del(int i);
     CANTERA_CAPI int reactor_copy(int i);
     CANTERA_CAPI int reactor_setInitialVolume(int i, double v);
+    CANTERA_CAPI int reactor_setChemistry(int i, bool cflag);
     CANTERA_CAPI int reactor_setEnergy(int i, int eflag);
     CANTERA_CAPI int reactor_setThermoMgr(int i, int n);
     CANTERA_CAPI int reactor_setKineticsMgr(int i, int n);
diff --git a/src/matlab/reactormethods.cpp b/src/matlab/reactormethods.cpp
index 5bdc06f6d..b151fe4cd 100644
--- a/src/matlab/reactormethods.cpp
+++ b/src/matlab/reactormethods.cpp
@@ -48,6 +48,9 @@ void reactormethods(int nlhs, mxArray* plhs[],
         case 7:
             iok = reactor_setKineticsMgr(i, int(v));
             break;
+        case 8:
+            iok = reactor_setChemistry(i, bool(v));
+            break;
         case 9:
             iok = reactor_setEnergy(i, int(v));
             break;