The Hydrogenophilaceae are a family of Betaproteobacteria, with two genera. Like all Proteobacteria they are Gram-negative. Hydrogenophilus are thermophilic, growing around 50 °C and obtaining their energy from oxidizing hydrogen. It includes the genera Hydrogenophilus and Thiobacillus (see below for the removal of certain species).
Thiobacillus spp. can be used in pest control, such as potato scabs. If an affected area is treated with sulfur and Thiobacillus spp., the bacteria will oxidise the sulfur to sulfuric acid, which will destroy the pest, as the potato scabs cannot tolerate acidic conditions. Thiobacillus thioparus may contribute to the formation of acid rain through the oxidation of sulfur dioxide to sulfurous acid.
Hydrogenophilus thermoluteolus is a facultative chemolithoautotroph that previously had only been found in hot springs. However, it was isolated in 2004 from ice core samples retrieved from a depth of ~3 km under the ice layer covering Lake Vostok in Antarctica. The presence of this thermophilic bacteria in the ice suggests that a geothermal system exists beneath the cold water body of Lake Vostok.
Obsolete Thiobacillus species 
- "Thiobacillus thiooxidans" was moved to Acidithiobacillus
- "Thiobacillus neapolitanus" was moved to Halothiobacillus
- "Thiobacillus tepidarius" was moved to Thermithiobacillus
- Bulat, Sergey A. Bulat; Irina A. Alekhina, Michel Blot, Jean-Robert Petit, Martine de Angelis, Dietmar Wagenbach, Vladimir Ya. Lipenkov, Lada P. Vasilyeva, Dominika M. Wloch, Dominique Raynaud and Valery V. Lukin (August 2004). "DNA signature of thermophilic bacteria from the aged accretion ice of Lake Vostok, Antarctica: implications for searching for life in extreme icy environments". International Journal of Astrobiology 3: 1–12. doi:10.1017/S1473550404001879. Retrieved 2011-01-29.
- Kelly, D.P., and Wood A.P. Reclassification of some species of Thiobacillus to the newly designated genera Acidithiobacillus gen. nov., Halothiobacillus gen. nov. and Thermithiobacillus gen. nov. Int. J. Syst. Evol. Microbiol. (2000) 50:511-516. PDF.