RECENTLY, with growing crisis in fossil fuel and the consequent of environmental pollution problems worldwide, bioethanol has become one of the most promising biofuels and many researchers have worked on improving the efficacy of the bioethanol production process. This work was concerned with producing bioethanol from low-cost raw agro-industrial feedstock (sugarcane bagasse and potato peels) and utilizing radiation technology to increase conversion rate of these materials to bioethanol. Both of sugarcane bagasse and potato peels were acid-hydrolyzed and resulted hydrolysates were fermented by either Zymomonas mobilis ATCC 29191, Saccharomyces cerevisiae ATCC 7754, or both organisms, cocultured (1:1). The effect of gamma irradiation on bioethanol production was studied by exposing the feedstock to different doses of gamma rays (0, 25, 50 75 kGy). Effect of combining gamma irradiation with acid treatment of feedstock on bioethanol production was also investigated. From sugarcane bagasse, the highest achieved final bioethanol concentration (15.4 gL-1) was obtained from the combined pretreatment by irradiation with 75 kGy followed by hydrolysis with 2 % (v/v) H2SO4 at 120°C for 60 min and fermented with co-culture (1:1) of Z. mobilis ATCC 29191 and Sacch. cerevisiae ATCC 29191. On the other hand, from potato peels the highest bioethanol concentration (12.1 g L-1) was obtained from combined pretreatment by irradiation with 75 kGy and hydrolyzed by 6 % (v/v) H2SO4 at 100°C for 60 min then fermented with co-culture (1:1).