Growth of Penicillium camembertii has been studied at the surface of a gelified medium. The Verlhust (or logistic) model has been tested and validated for the fitting of substrates consumption (lactate and peptone), ammonia production and proton transfer kinetics. With the obtained fitted parameters, the logistic model has been also applied to fit the growth kinetic by means of two additional parameters: the global yield and a parameter alpha which characterized the linking between growth and substrate consumption (or production). Instantaneous yield biomass on substrate (or product) can be deduced from the model. The yields remained constant on the whole culture when there is a total linking between the consumption (or production) and growth. It is almost the case for peptone consumption, and then a low value for the parameter alpha is observed. The model also allowed a fine analysis of the different growth phases. (C) 2002 Elsevier Science Ltd. All rights reserved.