Biomethanation process is a promising eco-friendly solution for the treatment of organic biomass which leads to efficient bioenergy production. However, this technology is necessary to clarify the best operational conditions and suitable reactors for treating the target substrates in order to make the technology assessable to rural areas. Present review is dedicated to focus the various techniques, which can be used to solve the constraints occurring during the gas production and help to enhance gas production. Brief description of possible pretreatments for converting complex lignocellulosic waste to biogas and desired range of operational parameters which are required to enhance the anaerobic digestion are discussed. Further suitable reactors for different substrates have also been analyzed. (C) 2012 Elsevier Ltd. All rights reserved.