The data files support the study “Electromethanogenesis from H₂S-containing biogas: H₂S and cathode potential drive microbial selection and methane yields.” They correspond to two H-type microbial electrosynthesis (MES) reactors (1 L cathodic volume) equipped with stainless steel mesh cathodes and operated for bioelectrochemical biogas upgrading and desulfurization. The reactors were run in fed-batch mode—initially with 99.9% CO₂ to establish electromethanogenesis, followed by synthetic biogas mixtures (CO₂ 40%/CH₄ 60%) and CO₂/CH₄/H₂S (1%) to assess upgrading and H₂S tolerance. Cathode potentials were stepwise lowered during CO₂ operation (–0.85, –0.90, –0.95 V vs Ag/AgCl) and maintained at –0.95 V vs Ag/AgCl thereafter.

The uploaded datasets include:

1) Bioinformatics outputs: microbial community composition and diversity across the distinct operational phases of each reactor.

2) Metadata files: physicochemical parameters corresponding to each sequenced microbial sample (e.g., pH, sulfide concentration, gas composition, applied potential, and cycle information).