diff --git a/src/thermophysicalModels/reactionThermo/mixtures/dieselMixture/dieselMixture.C b/src/thermophysicalModels/reactionThermo/mixtures/dieselMixture/dieselMixture.C
index 014ef3da51..8c698065a1 100644
--- a/src/thermophysicalModels/reactionThermo/mixtures/dieselMixture/dieselMixture.C
+++ b/src/thermophysicalModels/reactionThermo/mixtures/dieselMixture/dieselMixture.C
@@ -50,9 +50,9 @@ Foam::dieselMixture<ThermoType>::dieselMixture
 
     stoicRatio_(thermoDict.lookup("stoichiometricAirFuelMassRatio")),
 
-    fuel_(thermoDict.lookup("fuel")),
-    oxidant_(thermoDict.lookup("oxidant")),
-    products_(thermoDict.lookup("burntProducts")),
+    fuel_(thermoDict.subDict("fuel")),
+    oxidant_(thermoDict.subDict("oxidant")),
+    products_(thermoDict.subDict("burntProducts")),
 
     mixture_("mixture", fuel_),
 
@@ -91,9 +91,9 @@ const ThermoType& Foam::dieselMixture<ThermoType>::mixture
 template<class ThermoType>
 void Foam::dieselMixture<ThermoType>::read(const dictionary& thermoDict)
 {
-    fuel_ = ThermoType(thermoDict.lookup("fuel"));
-    oxidant_ = ThermoType(thermoDict.lookup("oxidant"));
-    products_ = ThermoType(thermoDict.lookup("burntProducts"));
+    fuel_ = ThermoType(thermoDict.subDict("fuel"));
+    oxidant_ = ThermoType(thermoDict.subDict("oxidant"));
+    products_ = ThermoType(thermoDict.subDict("burntProducts"));
 }
 
 
diff --git a/src/thermophysicalModels/reactionThermo/mixtures/egrMixture/egrMixture.C b/src/thermophysicalModels/reactionThermo/mixtures/egrMixture/egrMixture.C
index 06cf80a47f..7550ebf442 100644
--- a/src/thermophysicalModels/reactionThermo/mixtures/egrMixture/egrMixture.C
+++ b/src/thermophysicalModels/reactionThermo/mixtures/egrMixture/egrMixture.C
@@ -50,9 +50,9 @@ Foam::egrMixture<ThermoType>::egrMixture
 
     stoicRatio_(thermoDict.lookup("stoichiometricAirFuelMassRatio")),
 
-    fuel_(thermoDict.lookup("fuel")),
-    oxidant_(thermoDict.lookup("oxidant")),
-    products_(thermoDict.lookup("burntProducts")),
+    fuel_(thermoDict.subDict("fuel")),
+    oxidant_(thermoDict.subDict("oxidant")),
+    products_(thermoDict.subDict("burntProducts")),
 
     mixture_("mixture", fuel_),
 
@@ -101,9 +101,9 @@ void Foam::egrMixture<ThermoType>::read(const dictionary& thermoDict)
 {
     stoicRatio_ = thermoDict.lookup("stoichiometricAirFuelMassRatio");
 
-    fuel_ = ThermoType(thermoDict.lookup("fuel"));
-    oxidant_ = ThermoType(thermoDict.lookup("oxidant"));
-    products_ = ThermoType(thermoDict.lookup("burntProducts"));
+    fuel_ = ThermoType(thermoDict.subDict("fuel"));
+    oxidant_ = ThermoType(thermoDict.subDict("oxidant"));
+    products_ = ThermoType(thermoDict.subDict("burntProducts"));
 }
 
 
diff --git a/src/thermophysicalModels/reactionThermo/mixtures/homogeneousMixture/homogeneousMixture.C b/src/thermophysicalModels/reactionThermo/mixtures/homogeneousMixture/homogeneousMixture.C
index e72edf4b24..51705086b2 100644
--- a/src/thermophysicalModels/reactionThermo/mixtures/homogeneousMixture/homogeneousMixture.C
+++ b/src/thermophysicalModels/reactionThermo/mixtures/homogeneousMixture/homogeneousMixture.C
@@ -84,8 +84,8 @@ const ThermoType& Foam::homogeneousMixture<ThermoType>::mixture
 template<class ThermoType>
 void Foam::homogeneousMixture<ThermoType>::read(const dictionary& thermoDict)
 {
-    reactants_ = ThermoType(thermoDict.lookup("reactants"));
-    products_ = ThermoType(thermoDict.lookup("products"));
+    reactants_ = ThermoType(thermoDict.subDict("reactants"));
+    products_ = ThermoType(thermoDict.subDict("products"));
 }
 
 
diff --git a/src/thermophysicalModels/reactionThermo/mixtures/inhomogeneousMixture/inhomogeneousMixture.C b/src/thermophysicalModels/reactionThermo/mixtures/inhomogeneousMixture/inhomogeneousMixture.C
index 2ef52c112d..a4cfa2e9c0 100644
--- a/src/thermophysicalModels/reactionThermo/mixtures/inhomogeneousMixture/inhomogeneousMixture.C
+++ b/src/thermophysicalModels/reactionThermo/mixtures/inhomogeneousMixture/inhomogeneousMixture.C
@@ -51,9 +51,9 @@ Foam::inhomogeneousMixture<ThermoType>::inhomogeneousMixture
 
     stoicRatio_(thermoDict.lookup("stoichiometricAirFuelMassRatio")),
 
-    fuel_(thermoDict.lookup("fuel")),
-    oxidant_(thermoDict.lookup("oxidant")),
-    products_(thermoDict.lookup("burntProducts")),
+    fuel_(thermoDict.subDict("fuel")),
+    oxidant_(thermoDict.subDict("oxidant")),
+    products_(thermoDict.subDict("burntProducts")),
 
     mixture_("mixture", fuel_),
 
@@ -95,9 +95,9 @@ void Foam::inhomogeneousMixture<ThermoType>::read(const dictionary& thermoDict)
 {
     stoicRatio_ = thermoDict.lookup("stoichiometricAirFuelMassRatio");
 
-    fuel_ = ThermoType(thermoDict.lookup("fuel"));
-    oxidant_ = ThermoType(thermoDict.lookup("oxidant"));
-    products_ = ThermoType(thermoDict.lookup("burntProducts"));
+    fuel_ = ThermoType(thermoDict.subDict("fuel"));
+    oxidant_ = ThermoType(thermoDict.subDict("oxidant"));
+    products_ = ThermoType(thermoDict.subDict("burntProducts"));
 }
 
 
diff --git a/src/thermophysicalModels/reactionThermo/mixtures/multiComponentMixture/multiComponentMixture.C b/src/thermophysicalModels/reactionThermo/mixtures/multiComponentMixture/multiComponentMixture.C
index a30dd5dd1b..19f78a00c5 100644
--- a/src/thermophysicalModels/reactionThermo/mixtures/multiComponentMixture/multiComponentMixture.C
+++ b/src/thermophysicalModels/reactionThermo/mixtures/multiComponentMixture/multiComponentMixture.C
@@ -38,7 +38,7 @@ const ThermoType& Foam::multiComponentMixture<ThermoType>::constructSpeciesData
         speciesData_.set
         (
             i,
-            new ThermoType(thermoDict.lookup(species_[i]))
+            new ThermoType(thermoDict.subDict(species_[i]))
         );
     }
 
@@ -155,7 +155,7 @@ void Foam::multiComponentMixture<ThermoType>::read
 {
     forAll(species_, i)
     {
-        speciesData_[i] = ThermoType(thermoDict.lookup(species_[i]));
+        speciesData_[i] = ThermoType(thermoDict.subDict(species_[i]));
     }
 }
 
diff --git a/src/thermophysicalModels/reactionThermo/mixtures/veryInhomogeneousMixture/veryInhomogeneousMixture.C b/src/thermophysicalModels/reactionThermo/mixtures/veryInhomogeneousMixture/veryInhomogeneousMixture.C
index 3684fc3e09..942f98cc7b 100644
--- a/src/thermophysicalModels/reactionThermo/mixtures/veryInhomogeneousMixture/veryInhomogeneousMixture.C
+++ b/src/thermophysicalModels/reactionThermo/mixtures/veryInhomogeneousMixture/veryInhomogeneousMixture.C
@@ -51,9 +51,9 @@ Foam::veryInhomogeneousMixture<ThermoType>::veryInhomogeneousMixture
 
     stoicRatio_(thermoDict.lookup("stoichiometricAirFuelMassRatio")),
 
-    fuel_(thermoDict.lookup("fuel")),
-    oxidant_(thermoDict.lookup("oxidant")),
-    products_(thermoDict.lookup("burntProducts")),
+    fuel_(thermoDict.subDict("fuel")),
+    oxidant_(thermoDict.subDict("oxidant")),
+    products_(thermoDict.subDict("burntProducts")),
 
     mixture_("mixture", fuel_),
 
@@ -96,9 +96,9 @@ void Foam::veryInhomogeneousMixture<ThermoType>::read
     const dictionary& thermoDict
 )
 {
-    fuel_ = ThermoType(thermoDict.lookup("fuel"));
-    oxidant_ = ThermoType(thermoDict.lookup("oxidant"));
-    products_ = ThermoType(thermoDict.lookup("burntProducts"));
+    fuel_ = ThermoType(thermoDict.subDict("fuel"));
+    oxidant_ = ThermoType(thermoDict.subDict("oxidant"));
+    products_ = ThermoType(thermoDict.subDict("burntProducts"));
 }