A model adequately describing the lipase production by Candida rugosa has been developed, calibrated and validated using new experimental data. Process modelling has been done using CAMBIO software (Computer Aided Modelling of BIOprocesses), allowing to easy and interactively test various hypothesis and reaction schemes. Olive oil, oleic acid and glycerol has been used as substrates. The model satisfactorily describes the time evolution of biomass growth as well as lipase production in all cases. In particular diauxic behavior is successfully characterized. Model development process has helped in obtaining a 3-fold increase in lipase production when using oleic acid as substrate instead of the original olive oil used. © 1992 Springer-Verlag.