This work assessed the feasibility of a hydrogenotrophic biogas process integrated with a membrane module in the external-loop design. The major scope was to conduct the investigation from the perspective of the membrane unit and reveal how the operating strategy influences the efficiency of biogas formation. It was observed that the fermenter worked with an improved efficacy, indicated by the higher concentration of methane in the headspace (80-90%) when the gas loading intensity, defined as the ratio of inlet gas permeation rate and the circulation rate of the liquid phase, was adjusted to lower values (3-5.3 x 10(-3)). Such results are implying that the mass transfer of H-2 into the reactor is dependent on this critical parameter. Moreover, attention should be paid to the fouling of the module under longer-term experiments to keep its performance at a sufficient level.