A mathematical description of the principal kinetics involved in gibberellic acid and bikaverin production in an airlift bioreactor was attained using a non-structured model. Growth, dextrose and nitrogen consumption, and gibberellic acid and bikaverin production kinetics were considered for this purpose. Experimental data were obtained from submerged batch fermentation of the fungus Gibberella fujikuroi (CDBB H-984) and were fitted to three different sigmoidal models: 2-and 3-parameter Gompertz models and a logistic model. The most appropriate model was determined by means of an F test using growth kinetic fitting. The 2-parameter Gompertz model was found to be the most suitable and was used for both dextrose and nitrogen consumption, and gibberellic acid and bikaverin production fitting. A sensitivity analysis was performed to determine the effect of the parameters in the global model. The parameters of the 2-parameter Gompertz model were transformed in order to give them a biological meaning. (C) 2008 Elsevier Ltd. All rights reserved.