Thermosulfuriphilus ammonigenes ST65 T is an anaerobic thermophilic bacterium isolated from a deep-sea hy-drothermal vent chimney. T. ammonigenes is an obligate chemolithoautotroph utilizing elemental sulfur as an electron donor and nitrate as an electron acceptor with sulfate and ammonium formation. It also is able to grow by disproportionation of elemental sulfur, thiosulfate and sulfite. Here, we present the complete genome sequence of strain ST65 T. The genome consists of a single chromosome of 2,287,345 base pairs in size and has a G + C content of 51.9 mol%. The genome encodes 2172 proteins, 48 tRNA genes, and 3 rRNA genes. Genome analysis revealed a complete set of genes essential to CO 2 fixation and gluconeogenesis. Homologs of genes encoding known enzyme systems for nitrate ammonification are absent in the genome of T. ammonigenes assuming unique mechanism for this pathway. The genome of strain ST65 T encodes a complete set of genes necessary for dissimilatory sulfate reduction, which are probably involved in sulfur disproportionation and anaerobic oxidation. This is the first reported genome of a bacterium from the genus Thermosulfuriphilus, providing insights into the microbial contribution into carbon, sulfur and nitrogen cycles in the deep-sea hydro-thermal vent environment.