Coir pith is a lignocellulosic agro residue, which is produced in enormous quantities as a byproduct in coir industry of India. Though utility of coir pith has been claimed in different applications, an efficient and accepted technology for its maximum utilization is not yet made available. Objective of the study was to check the feasibility of biomethanation of coir pith and to investigate the conditions for improved digestion. The study shows that, without any pretreatment, substrate could sustain the anaerobic digestion process with the methane yield of about 38.1 per kilogram dry weight after 44 days. Reduction in the particle size improved methane yield about 1.5 times compared to natural sample. Whereas acid treatment suppressed methane formation, alkali treatment has resulted in a slight improvement. In short, the present work does give affirmative results and scopes for the process of biomethanation with the conclusion that more research efforts can transform coir pith into a good renewable energy resource.