Biogas has been one of the promising renewable fuel produced from organic substrates. Cocoa husk has a potential to be a substrate for biogas production. Based on various studies, cocoa husk has the potential as a substrate for methane production from anaerobic co-digestion. However, lower biodegradation efficiency of anaerobic co-digestion of cocoa husks was affected by high cell wall content of cellulose and association between cellulose and lignin, which would hinder the anaerobic microbes to convert cocoa husk into methane. Cow rumen fluid has been proposed for method for biodegradation of lignocellulosic biomass, since it has advantages in degradation of plant material by the Fiblolytic enzymes from the rumen ecosystem. The ratio of cocoa husk to cow manure are as follows, 1:3, 1:1, 3:1, and 1:0, where the substrate used for all four variations is 100g, the variation of substrate to cow rumen fluid is also applied with the following ratio 1:1, 1:0, 2:1, 1:2, and incubation operating temperature is as follow 25°C, 37°C, 50°C, and 70°C. This research would see the potential of cocoa husk as a substrate, and the effect that will happen if cow rumen fluid is used as its inoculum, and to know if there is an increase in efficiency of digestion, in form of higher solids degradation and higher biogas methane composition. The purpose of this research is to know the optimum ratio between cow manure and cocoa husk and feasibility of rumen fluid as inoculum. Based on the results of the research, the following can be concluded: The optimum ratio of cocoa husk to cow manure is 1:1, the optimum ratio of substrate to cow rumen fluid is 1:1, and the optimum temperature for biogas production incubation is 37°C or mesophilic condition.