Batch kinetics of polyhydroxybutyrate (PHB) synthesis in a bioreactor under controlled conditions of pH and dissolved oxygen gave a biomass of 14 g l(-1) with a PHB concentration of 6.1 g l(-1) in 60 h. The data of the batch kinetics was used to develop a mathematical model, which was then extrapolated to fed-batch by incorporating the dilution due to substrate feeding. Offline computer simulation of the fed-batch model was done to develop the nutrient feeding strategies in the fed-batch cultivation. Fed-batch strategies with constant feeding of only nitrogen and constant feeding of both nitrogen and fructose were tried. Constant feeding strategy for nitrogen and fructose gave a better PHB production rate of 0.56 g h(-1) over the value obtained in batch cultivation (PHB production rate -0.4 g h(-1)). (C) 2007 Elsevier Ltd. All rights reserved.