Batch digestion of municipal garbage was carried out for 100 days at room temperature (26 +/- 4 degreesC; average temperature 25 degreesC) and at ambient temperature (32 +/- 10 degreesC; average temperature 29 degreesC) conditions for total solids concentrations varying between 45 and 135 g/l. A first order model based on the availability of substrate as the limiting factor was used to perform the kinetic studies of batch anaerobic digestion system. Effect of organic solids concentration and digestion time on biogas yield was studied and mass and energy balance analysis was conducted for batch digestion. The net bioenergy yield from municipal garbage and corresponding bioprocess conversion efficiency over the length of the digestion time were observed to be 12,528 kJ/kg volatile solids and 84.51% respectively. The methane content of the biogas generated from the reactors was in the range of 62-72% with the overall average methane content of the biogas, computed over the total digestion period was 65 vol%. (C) 2004 Published by Elsevier Ltd.