A bacterial isolate, strain TU-7T, with an optimum growth temperature of about 45-50 degrees C and an optimum pH for growth between 8.0 and 8.5, was recovered from a hot spring in the Furnas area of the island of São Miguel in the Azores. The new isolate is non-pigmented, facultatively chemolithoorganotrophic, strictly aerobic and catalase- and oxidase-positive. The organism oxidized thiosulfate to sulfate with enhancement of growth. This organism assimilated organic acids but did not assimilate carbohydrates or polyols. 16S rRNA gene sequence analysis placed strain TU-7T within the radiation of the Alphaproteobacteria as a deep branch of the family Acetobacteriaceae. The major fatty acids of strain TU-7T are 18 : 1 omega 7c, 18 : 0, 19 : 0 cyclo omega 8c and an aliphatic chain with an equivalent chain-length of 20.195, identified as 19 : 0 2-OH cyclo omega 8 (Delta 11 : 12). Ubiquinone 10 is the major respiratory quinone and the major polar lipids are phosphatidylcholine, phosphatidylethanolamine, diphosphosphatidylglycerol and phosphatidylglycerol in addition to two unidentified aminolipids. Bacteriochlorophyll a and puf genes were not detected. Based on 16S rRNA gene sequence analysis and physiological and biochemical characteristics, we describe a novel species of a new genus represented by strain TU-7T, for which we propose the name Elioraea tepidiphila gen. nov., sp. nov. The type strain of Elioraea tepidiphila is strain TU-7T (=DSM 17972T =CIP 109115T).