The potentials of dead neem leaves for the production of the biogas was investigated as key measure to reduce the deforestation mainly caused by firewood cuttings in the Far-North Cameroon. Biomass collected was allowed to undergo biological pretreatment to facilitate its hydrolysis during anaerobic co-digestion with the cow dung. Samplings of dead neem leaves were taken after 0, 5, 10, 15, 20 and 30 days of pretreatment. Collected substrates from the pretreatment unit were used to feed 1.5L micro-bioreactors in three doses namely 5%, 15% and 25%. The gross volume and flammable gas produced was evaluated. The pH of the various treatments was measured. Data on production were analyzed using SPSS 20.0 software at 5% level of significance. It appears from this study that the pretreated leaves supplied biogas just as from 4 days after digestion, while those which did not undergo this pretreatment started producing biogas after more than 3 weeks. In terms of the amount of the generated biogas, the15 days pretreated substrate produced 3158 ml which was 22%, 35% and 94% higher than those of non-pretreated leaves, mechanically pretreated leaves and cow dung respectively. With regard to the change in pH within the bioreactors, pH dropped to 4 during the co-digestion of non-biologically pretreated leaves. At the same time in bioreactors where the substrate was biologically pretreated, the pH was more stable and appropriate for the biogas production and varied around 6 and7.