This study focused on a strain belonging to a genus and class (Dissulfuribacteria) of Desulfobacterota other than those on which functional studies of sulfur disproportionation have been conducted before. Dissulfuribacter thermophilus strain S69T, which was the subject of a comparative proteomic analysis, is notable for its ability to grow by disproportionation of sulfite, thiosulfate and elemental sulfur [19]. Here, we investigated the proteomic landscape of this strain during growth via thiosulfate disproportionation (S2O3D) and in the hydrogenotrophic sulfite-containing condition (hSO3), and examined the associated sulfur chemical intermediates. Using a combination of cultivation and proteomic and analytical approaches, we provide novel insights into the physiological and biochemical mechanisms involved in these sulfur metabolism pathways.