Methane production in the rumen is characterized by microbial interspecies electron transfer. The dominant process involves the electron shuttles dihydrogen and formate produced by bacteria and protozoa. These electron shuttles are then used by their syntrophic archaeal partners to produce methane. In the rumen, however, the extent and importance of shuttle-free electron transfers, described in other methanogenic environments, is not known. We tested the effect of conductive materials for highlighting possible direct interspecies electron transfer (DIET) in the rumen ecosystem. We used in vitro and in sacco experiments to evaluate rumen fermentation and shifts in microbial community composition, respectively. The in vitro batch culture technique used four cannulated sheep as donors of ruminal fluid. Treatments were substrate alone (Control, 400 mg alfalfa:wheat; 3:1 ratio in 40 mL buffer-rumen fluid mixture) or supplemented with 5 and 10% (substrate basis) of granular activated charcoal (GAC), graphene (GPH) or magnetite (MAG) powders. For the in sacco experiment, membranes of the inert polymer polydimethylsiloxane containing conductive materials were incubated in the rumen of four sheep for 1, 7, and 28 days followed by amplicon sequencing. In vitro methane production increased by 8.2% with GPH_10% and by ~7.4% with MAG_5% or MAG_10% as compared to control (P=0.002). In contrast, total gas and VFA production and proportions of VFA were unaffected by conductive materials (P>0.05). For microbes adhering to membranes following rumen incubation, main differences were observed for the Euryarchaeota phylum with higher relative abundance for GAC and GPH compared to control. Concurrently, major discriminant taxa were mainly associated to the Euryarchaeota. The increase in methane production without other fermentation changes and the shift in microbes associated to conductive materials may suggest a DIET mechanism. DIET should be validated with additional tools and its extent in the rumen assessed as it could be another mechanism to consider for modulating methanogenesis.