Biomethanation converts carbon dioxide (CO 2 ) emissions into renewable natural gas (RNG) using mixed microbial cultures enriched with hydrogenotrophic archaea. This study examines the performance of a single methanogenic archaeon converting biogas with added hydrogen (H 2 ) into methane (CH 4 ) using a trickle-bed bioreactor with enhanced gas-liquid mass transport. The process in continuous operation followed the theoretical reaction of hydrogenotrophic methanogenesis (CO 2 + 4 H 2 → CH 4 + 2 H 2 O), producing RNG with over 99 % CH 4 and more than 0.9 H 2 conversion efficiency. The Monod constants of H 2 uptake were experimentally determined using kinetic modelling. Also, a dimensionless parameter was used to quantify the ratio between the H 2 mass transfer rate and the maximum attainable H 2 consumption rate. Single-culture biomethanation averts the formation of secondary metabolites and bicarbonate buffer interferences, resulting in lower demands for H 2 than mixed-culture biomethanation.