Radiation crosslinked 2-hydroxyethyl methacrylate/acrylamide (HEMA/AAm) copolymers prepared by gamma-irradiation were used in experiments on swelling, diffusion, immobilization of yeast cells (Saccharomyces cerevisiae) and production of ethyl alcohol. HEMA/AAm hydrogels irradiated at 3 kGy were used for swelling and diffusion studies in water and the nutrient medium of the cells. The parameters of equilibrium swelling, maximum swelling, initial swelling rate, diffusional exponent, network constant and diffusion coefficient of the hydrogel/penetrant systems were calculated and evaluated. All parameters for the hydrogel/water system were higher than that of the hydrogel/nutrient medium systems. Yeast cells (Saccharomyces cerevisiae) were immobilized on to the hydrogels by adsorption during multiplication and ethyl alcohol production of the hydrogels was investigated. Swelling of HEMA increased with the addition of AAm and ethyl alcohol production increased with increasing AAm in the hydrogels. (C) 2002 Elsevier Science Ltd. All rights reserved.