The applicability of respirometry to characterize fungal growth kinetics was studied using Penicillium chrysogenum as the model microorganism. Oxygen uptake data were used in conjunction with a nonlinear parameter estimation technique to determine the kinetic parameters associated with microbial growth. The theoretical model that used the Contois equation for microbial growth was able to accurately describe experimental oxygen uptake data. Penicillium chrysogenum was characterized by average values of 0.195 h(-1) and 4.13 for the maximum specific growth rate, mu(max), and the Contois saturation coefficient, K-c, respectively. The average true growth yield was 0.405 mg mg(-1). As only oxygen uptake information is required for biokinetic parameter estimation, respirometry is a very convenient tool for studying microbial growth as high quality experimental data can be obtained with relatively little experimental effort.