The invention relates to a method for increasing biogas production of thermophilic anaerobe systems. More closely, a biomass containing a consortium comprising polymer-degrading, acetogenic and methanogenic microorganisms is inoculated with a microorganism culture before the start of or during biogas production. Said microorganism is a thermophilic, acetogenic, hydrogen producing bacterium. As an example, Caldicellulosiruptor saccharolyticus is applied. According to the invention production if methane containing biogas is significantly increased. The invention is useful for intensifying biogas production and thereby increasing its feasibility.