The optimum mesophilic temperature of biogas production from blends of agro-based wastes was determined under constant supply of heat. Cassava waste water (CW), Brewery spent grain (BS), Powdered rice husk (PR), Cow dung liquor (CD) and Swine dung (SD) were blended in the ratios of CW: SD (2:3), BS: PR (1:1) and BS: CD (1:3). Biogas production from the waste blends was monitored under the mesophilic temperatures of 25, 30, 35 and 40°C. Results obtained indicate steady increase in biogas production at temperatures of 35 and 40°C for all the blends while maximum cumulative gas yield was observed at the temperature of 40°C. The BS:CD blend gave the highest biogas yield of 2.51 L followed by the BS: PR blend with the cumulative yield of 1.21 L. The CS: SD blend had the least cumulative biogas yield of 1.13 L. These results indicate that increased and steady biogas production can be achieved under the optimum mesophilic temperature of 40°C when these agro-based wastes are blended in different proportions.