The present invention discloses activated carbon-metal organic framework composite materials (AC@MOF) with enhanced gas adsorption capacity. The present invention also discloses a process for the preparation of carbon-metal organic framework composite materials (AC@MOF). The present invention involves the use of “void space filling method” in metal organic frameworks (MOFs), which have been accomplished by in-situ addition of selected type and appropriate amount of activated carbon during the synthesis of MOF such as Cu-BTC, in the storage of gases such as methane. The gas adsorption capacity of these AC@MOF composite materials is significantly increased through this method.