Biomethane produced by anaerobic digestion of organic waste is a renewable and sustainable energy that can supplement global energy needs. Existing literature shows that different mixing ratios of the same co-substrates have an impact on biomethane production. In this study, the impact of different mixing ratios of cattle blood and rumen contents on biomethane production was investigated. The physicochemical characteristics of seven samples with different blood and rumen contents were determined. Their biomethane yield was then assessed in laboratory-scale batch digesters at 37 o C (mesophilic). The biomethane yields of the samples gave a mean value of 11.25±13.34 which indicates significant variability (p < 0.05). The sample containing 10 ml of bovine blood and 50 ml of rumen contents (S 6 ) gave the highest biomethane yield and can be considered for optimization of biomethane production from these feedstocks.