Abstract: Method and apparatus for reducing chemical reaction mechanisms are disclosed. A method comprises obtaining data for one or more chemical species in a chemical reaction model from a database, the database including properties of the one or more chemical species; grouping the chemical species in a chemical reaction model into one or more isomer groups according to molecular properties of the chemical species; assigning a representative isomer to at least one isomer group; replacing, in one or more chemical reaction equations of the chemical reaction model, one or more groups of chemical species with a corresponding representative isomer; and executing the chemical reaction model by an apparatus to determine results.