A computer model which has previously been developed and used to model diesel engine performance has been modified to model dual fuel combustion processes. Results of the model are compared with the experimental performance of a single cylinder dual fuel engine.The original diesel model (SPICE - developed at the University of Bath) simulates the ignition delay period and the diesel combustion process using “zero-dimensional” sub-models. The development of the model to simulate dual fuel combustion has retained the same zero-dimensional approach. In the case of the dual fuel simulation, however, the combustion process models combustion of the premixed gas/air charge as well as the premixed and diffusion components of the diesel fuel combustion.The model has been verified by comparison against results from a single cylinder direct injection engine. Data are compared for engine brake power, brake thermal efficiency and ignition delay period. Data for both diesel and dual fuel operation of the same engine are compared.