This article presents the influence of temperature and influent substrate composition on the produced biogas volume in an anaerobic co-digestion process. Four cases of anaerobic digestion were considered. Digestion of waste sludge only and anaerobic co-digestion of sludge mixed with solid waste in mesophilic (T=35 degrees C) and thermophilic (T=55 degrees C) phases. The obtained results show that thermophilic co-digestion gives the best results; although the temperature has an effect on biogas production, it remains however quite relative compared to the effect of solid waste. They confirm, surely, that the combined effect of temperature and solid waste improves considerably the biogas production rate (GPR). Changing conditions from mesophilic to thermophilic ones for waste sludge alone and for waste sludge mixed with solid waste results in an increase of the GPR from 0.18 to 0.39m(3)/m(3).d and from 0.29 to 0.96m(3)/m(3).d, respectively. Copyright (c) 2013 John Wiley & Sons, Ltd.