Rhodobacter sphaeroides O.U. 001 (concentration of inoculum-0.36 g dry wt/l) and brewery wastewaters were applied in photobiogeneration of hydrogen under illumination of 116 W/m(2). The best results were obtained with filtered wastewaters sterilized at 120 degrees C for 20 min and maximal concentration of waste in medium equal 10% v/v. The main product in generated biogas was hydrogen (90%). After sterilization the amount of generated hydrogen was tripled (from 0.76 to 2.2 l H(2)/l medium), whereas waste concentration of 10% v/v resulted in the best substrate yield (0.22 l H(2)/l of waste). Under these conditions the amount of generated hydrogen was 2.24 l H(2)/l medium and light conversion efficiency reached value of 1.7%. The modified Gompertz equations served in modeling of the kinetics of the studied process. (C) 2010 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved.