A thermophilic, anaerobic, chemolithoautotrophic bacterium (strain Sh68T) was isolated from a hydrothermal pond at Uzon Caldera, Kamchatka, Russia using anoxic medium with elemental sulfur as the only energy source. Cells of strain Sh68T were Gram-negative rods, 0.5 to 0.8 ?m in diameter and 1.2 to 2.0 ?m in length, motile with flagella. The temperature range for growth was 30-65oC, with an optimum at 50-52oC. The pH range for growth was 5.2-7.5, with an optimum growth at 6.0-6.2. Growth of strain Sh68T was observed at NaCl concentrations ranging from 0 to 2.3% (w/v). Strain Sh68T grew anaerobically with elemental sulfur as an energy source and bicarbonate/CO2 as a carbon source. Elemental sulfur was disproportionated to sulfide and sulfate. The growth was enhanced in the presence of poorly crystalline Fe(III) oxide (ferrihydrite) as a sulfide-scavenging agent. Strain Sh68T was also able to grow by disproportionation of thiosulfate and sulfite. Sulfate was not used as an electron acceptor neither with H2 nor organic electron donors. Analysis of the 16S rRNA gene sequence revealed that the isolate belongs to the class Deltaproteobacteria and it most closely related to Dissulfuribacter thermophilus (90.0% sequence similarity). On the basis of its physiological properties and results of phylogenetic analyses, strain Sh68T is considered to represent a novel species of a new genus, for which the name Dissulfurimicrobium hydrothermale gen. nov., sp. nov. is proposed. The type strain of Dissulfurimicrobium hydrothermale is Sh68T (=JCM 19990T =VKM B-2854T). This is the first description of sulfur-disproportionating thermophile from a terrestrial ecosystem.