This paper presents a dynamic mathematical model of activated sludge which is able to predict the formation and degradation kinetics of SMP and EPS in a bacterial biocenosis. The model is based on a calibrated version of ASM3 [1] and an extended unified theory of production and degradation of SMP and EPS as proposed by Laspidou and Rittmann [2, 3]. The model was calibrated on the published experimental data from batch and continuous flow laboratory and pilot plant experiments [4-6] and proved to be in good agreement with the measurements. A standard set of parameters was then chosen for the model as a combination of the calibrated values and literature data. The CES-ASM3 was then used to predict SMP and EPS production in an activated sludge system under various operating conditions. The simulations indicated an increased production of SMP and EPS at higher MISS, lower temperatures and lower SRT. The model also predicted a slight increase in SMP and EPS with increased DO. (C) 2010 Elsevier B.V. All rights reserved.