Coffee processing generates huge amount of solid and liquid waste in Ethiopia. These cause pollution problems in the receiving water bodies. However, the solid waste mainly contains organic matter which can be used for generation of energy. The present study was conducted to evaluate the effect of chemical and biological additives on the coffee pulp silage for biogas production. Coffee pulp were collected and mixed with additives and pre-conditioned for ensiling periods 10, 20 and 40 days. Then biogas production was carried out in batch systems under mesophilic temperature (38â°C) for two months. The treatments (T1 â€“ T4) were performed for 10 day ensiling period with T1 (control), T2 (biological additive), T3 (chemical additive) and T4 (both additives). In the treatments (T5-T8), the samples were extended for 20 day ensiling period with T5 (control), T6 (biological additive), T7 (chemical additive), T8 (both), and T9-T12 were at ensiling periods of 40 days with T9 control,T10 with biological additive,T11 addition of chemicals and T12 by the addition of both. T13 was the raw coffees pulp without ensiling .The maximum biogas production was realized at ensiling period of 40 days in T10 (2980ml).The minimum biogas was recorded at ensiling period of 10 days by the control (T1) of treatments, which was 634 ml. The percentage of methane produced were T1(57.2%),T2(56.1%),T3(39.1%),T4(60.1%), T5(33.4%), T6(44.3), T7(47.5%), T8(63.1%), T9(52.1%), T10(70%),T11(54%),T12(62.8%),T13(55.7%). The general biogas quality in ascending order for all treatments including the raw pulp was controlT5< T3< T6< T7< T9< T11< T13< T2< T1< T4