In this paper, models developed to determine exhaust emissions from Spark Ignition engines are shown. Concretely, a model based on chemical kinetics for determining CO and NOX emissions is presented. Also it is shown a model for the determination of the HC exhaust emissions based on retention in crevices, wall quenching, and in-cylinder and exhaust pipe post-flame combustion processes. Both models are included in a quasi-dimensional multizone model that permits the fast analysis and prediction of combustion in homogeneous-charge SI engines. Finally, results obtained from the models are compared with experimental exhaust emissions measured in a test bench.