A study was carried out to investigate the effect of pretreatment with plantain peel ash on biogas production from cow dung. Two portable floating drum digesters of the same capacity were used for the experiment. One was filled with substrate prepared from cow dung and the second was also filled with substrate prepared from cow dung but pretreated with plantain peel ash. Results showed that 11,998 cm3 of biogas was produced from the digester that contained substrate of cow dung only while 20,493 cm3 was produced from the digester that contained substrate pretreated with plantain peel ash. This showed that the increase in the volume of biogas producedas a result of plantain peel ash addition is 8,495 cm3 which is equivalent to 70.8%.