This paper presents a mathematical model applied to a continuous hydrogen production system, composed of a stirred fermenter connected to a biocatalyzed electrolysis cell (BEC). The model contemplates two differential equation systems which describe the adaptation (start-up) and continuous phases between the fermenter and the EEC. The proposed model describes the dynamics of hydrogen and volatile fatty acid (VFA) production and substrate consumption (glucose for the stirred fermenter and acetate in the BEG), based on a Tessier-type bacterial kinetic which simulates the lag phase in the bacteria. A hybrid evolutionary algorithm and least squares method were used to estimate the parameters. Model validation and simulation were achieved by obtaining the volumes of hydrogen and VFAs produced and the statistical bacterial density via the most probable number (MPN) method. (C) 2012 Elsevier Ltd. All rights reserved.