The growth and the intracellular biopolymer Poly-beta Hydroxybutyrate (PHB) storage kinetics of Alcaligenes eutrophus were studied in a batch cultivation process. NIC ratio was found to both limit and inhibit the growth of the culture. The effect of initial N/C on mu(max) was studied in the range 0.03-0.4. Maximum mu(max) was observed at NIC equal to 0.09. A structured mathematical model was proposed. The model parameters were evaluated using the actual batch fermentation data. The model was used to simulate nutrient feeding profiles for enhanced PHB production in a fed-batch fermentation.