The highest amount of biogas was obtained at a C/N ratio of 17 in the R2 reactor. The reactors operated without any setback; even at the lowest C/N value in R1, a considerable amount of gas was obtained. This could be because poultry litter is nutrient-rich and contains adequate amounts of carbon, oxygen, hydrogen, nitrogen, phosphorous, potassium, calcium, and magnesium as well as a number of trace elements that are essential for the growth of anaerobic bacteria