Most metabolic hydrogen ([2H]) produced in the rumen during microbial fermentation is directed toward methanogenesis. Because a decrease in methane (CH₄) production does not always result in better animal performance, the aim of this study was to understand the fate of [2H] when rumen methanogenesis is inhibited. Three chemical inhibitors with different modes of action (nitrate, NIT; 3-nitrooxypropanol, NOP; anthraquinone, AQ) were evaluated with the Rumen Simulation Technique (RUSITEC). The microbial community was adapted to the system for one week before measurements. Treatments and days fixed effects, and their interaction, were analyzed with the MIXED procedure of SAS, with vessel nested within treatment as random effect. Nitrate acts as a [2H] sink during its reduction to ammonia. Nitrate decreased CH₄ production (17.1 vs. 3.6 ± 0.84%, mean ± SEM; P < 0.001) and competed with other [2H]-consuming pathways (dissolved dihydrogen [H₂] and reduced volatile fatty acids [VFA] production) while increasing [2H]-producing pathways (acetate production). The efficiency of microbial nitrogen (N) production was also increased. Nitrooxypropanol inhibits the last step of CH₄ production in methanogenic Archaea. Nitrooxypropanol decreased methanogenesis (17.1 vs. 5.0 ± 0.84%; P < 0.001), increased both gaseous and dissolved H₂ concentration, and decreased acetate production, but increased butyrate and minor, reduced VFA (valerate, caproate and heptanoate). Anthraquinone disrupts bacterial membranes and inhibits bacterial protein synthesis, but its specific effect toward methanogenesis is not well understood. While moderately decreasing CH₄ production (17.1 vs. 12.6 ± 0.84%; P < 0.001), AQ increased gaseous H₂ production but lowered dissolved H₂ concentration suggesting a lack of relationship between both H₂ forms. Also, AQ increased ammonium concentration, and decreased total microbial N production and its efficiency. Overall, this study indicates that different methanogenesis inhibitors have dissimilar effects on the re-direction of [2H] spared from methanogenesis. Finally, as [2H] recovery of control treatment, NOP and AQ was largely lower than 100%, further studies are required to identify and quantify other [2H] sinks in the rumen.