Disclosed is a method for extending the life of dehydrogenation catalysts used to prepare vinyl aromatic hydrocarbons. The catalysts, which typically include both iron oxide and potassium containing catalysis promoter, are exposed to additional potassium delivered using a potassium carboxylate. The potassium carboxylates are desirably free of halogens and other catalysts poisons or groups that could result in the undesirable properties in vinyl aromatic hydrocarbons produced therewith. The present invention is particularly useful with the production of styrene and methyl styrene.