A two-stage, no-mix anaerobic digester of 155 l capacity was used to investigate the feasibility of biogas production and the pollution potential reduction of acid cheese whey. The digester was operated at a 15-day hydraulic retention time and three temperatures (19, 25, 35°C). Both the temperature and pH of the whey had significant effects on the performance of the digester. The quantity and quality of biogas can be improved by controlling the pH of the outlet chamber where the meth-anogenic process takes place.