NOVELTY - Converting biomass to methane and light hydrocarbons, comprises: (a) performing a fast pyrolysis of lignocellulosic biomass using a hydrogen-containing sweep gas; (b) passing the hot pyrolysis gas mixture containing hydrogen through a first section of a catalytic reactor to form a methane, steam and light hydrocarbon enriched gas stream; (c) providing an extended gas residence time of 10 seconds to 10 hours within a second section of the reactor; and (d) cooling and separating the gas stream to output methane-rich fuel gas and by-product condensed light hydrocarbons and light oxygenates.    USE - The method is useful for converting biomass to methane and light hydrocarbons (claimed), which are useful as fuel.    ADVANTAGE - The method simply and economically converts the biomass to methane and hydrocarbons at low temperature with high energy content and low level of depositable tars, avoids the formation of deposits downstream of thermochemical reactors, minimizes waste water discharges, and reduces disposal costs.    DETAILED DESCRIPTION - Converting biomass to methane and light hydrocarbons with low levels of depositable tars, comprises: (a) performing a fast pyrolysis of lignocellulosic biomass by a process comprising flash pyrolysis, fast pyrolysis or rapid pyrolysis using a hydrogen-containing sweep gas at a temperature of 400-600 degrees C and an elevated pressure of 3-50 atm to produce a hot pyrolysis gas mixture and a by-product containing char and ash; (b) passing the hot pyrolysis gas mixture containing hydrogen through a first section of a catalytic reactor to form a methane, steam and light hydrocarbon enriched gas stream at a temperature of 400-600 degrees C without addition of air or oxygen to induce the temperature rise; (c) providing an extended gas residence time of 10 seconds to 10 hours within a second section of the catalytic reactor at temperatures 400-650 degrees C; and (d) cooling and separating the gas stream to output a useful methane-rich fuel gas and by-product condensed light hydrocarbons and light oxygenates.