The objective of this study was to determine the possibility of applying macroalgae biomass originating from Bay of Puck, Poland, as a substrate in the methane fermentation process and to verify the impact of taxonomic structure and other physicochemical traits of the analyzed biomass on the technological effectiveness of the fermentation process. The efficiency of methane fermentation was determined using respirometric kits. In all periods of the vegetative season, the structure of macrophytobenthos was predominated by brown algae of the family Ectocarpaceae, namely Pilayella litoralis and Ectocarpus sp. The production of biogas fitted within a narrow range of 266.53 ± 16.43 cm 3 /g o.d.m. during fermentation of algae harvested in September and 285.71 ± 11.35 cm 3 /g o.d.m. in that from August. The percentage content of methane in biogas ranged from 57.28 ± 1.75% to 59.22 ± 2.84%. Regardless of macroalgae biomass harvest period, the postfermented sludge was characterized by similar values of the analyzed parameters.