diff --git a/src/thermophysicalModels/reactionThermo/chemistryReaders/chemkinReader/chemkinLexer.L b/src/thermophysicalModels/reactionThermo/chemistryReaders/chemkinReader/chemkinLexer.L
index 9361ed2e..570234f5 100644
--- a/src/thermophysicalModels/reactionThermo/chemistryReaders/chemkinReader/chemkinLexer.L
+++ b/src/thermophysicalModels/reactionThermo/chemistryReaders/chemkinReader/chemkinLexer.L
@@ -148,7 +148,7 @@ irreversibleReactionDelimiter {space}"=>"{space}
 startPDependentSpecie {space}"("{space}"+"{space}
 pDependentSpecie      {specieName}")"{space}
 reactionCoeffs        {space}{floatNum}{some_space}{floatNum}{some_space}{floatNum}{space}
-reactionKeyword       {space}[A-Za-z](([A-Za-z0-9)*-])|("("[^+]))*{space}
+reactionKeyword       {space}[A-Za-z](([A-Za-z0-9)*-])|("("[^+]))*((\+({some_space}))?){space}
 reactionKeywordSlash  {reactionKeyword}"/"{space}
 thirdBodyEfficiency   {space}{floatNum}{space}"/"{space}
 startReactionCoeffs   {space}"/"{space}