Some nutritional strategies focused on rumen methanogenesis inhibition results in hydrogen accumulation, a waste product that cannot be used by the animal. We hypothesised that the addition of an adequate electron acceptor can incorporate hydrogen into the production of useful metabolites. In this study, the potential use of phloroglucinol, a metabolite associated with plants’ hydrolysable tannins, as an alternative hydrogen acceptor which can be converted to acetate by rumen microbes was considered. A sequential batch incubation technique with three consecutive 24-h transfers was used to allow microbes to adapt to 36 mM phloroglucinol. Next, fourth and fifth consecutive incubations were conducted in the absence or presence of 3 μM methanogenesis inhibitor 2-bromoethanesulfonate (BES). Controls without phloroglucinol or BES showed minor accumulation of hydrogen, which increased significantly when methanogenesis was inhibited with BES, whereas the addition of phloroglucinol to BES-supplemented cultures generally decreased hydrogen accumulation. Surprisingly, phloroglucinol alone almost totally inhibited methane production and substantially increased hydrogen accumulation compared to control treatments. This is in accordance with a decrease in methanogens abundance detected by qPCR. In contrast, phloroglucinol increased total bacterial numbers and total volatile fatty acid (VFA) production, particularly due to increases in acetate and butyrate. Changes in VFA are in agreement with the disappearance of phloroglucinol in the medium (>80%). These results suggest that degradation of phloroglucinol can reduce hydrogen accumulation and produce more VFA when methane production is inhibited in vitro. Phloroglucinol supplementation also reduced methane production, probably by directly inhibiting methanogens The dual effect of phloroglucinol as a hydrogen acceptor and methanogenesis inhibitor can have practical applications in ruminant production.