Two isolates, belonging to a new species of a novel genus of the Phylum "Deinococcus/Thermus ", were recovered from hot spring runoffs on the Island of São Miguel in the Azores. Strains RQ-24(T) and TU-8 are the first cultured representatives of a distinct phylogenetic lineage within this phylum. These strains form orange/red colonies, spherical-shaped cells, have an optimum growth temperature of about 50 degrees C, an optimum pH for growth between about 7.5 and 9.5, and do not grow at pH below 6.5 or above pH 11.2. These organisms grow in complex media without added NaCl, but have a maximum growth rate in media with 1.0% NaCl and grow in media containing up to 6.0% NaCl. The organisms are extremely ionizing radiation resistant; 60% of the cells survive 5.0 kGy. These strains are chemoorganotrophic and aerobic; do not grow in Thermus medium under anaerobic conditions with or without nitrate as electron acceptor and glucose as a source of carbon and energy, but ferment glucose to D-lactate without formation of gas. The organisms assimilate a large variety of sugars, organic acids and amino acids. Fatty acids are predominantly iso- and anteiso-branched; long chain 1,2 diols were also found in low relative proportions; menaquinone 8 (MK-8) is the primary respiratory quinone. Peptidoglycan was not detected. Based on 16S rRNA gene sequence analysis, physiological, biochemical and chemical analysis we describe a new species of one novel genus represented by strain RQ-24(T) (CIP 108686(T)=LMG 22925(T)=DSM 17093(T)) for which we propose the name Truepera radiovictrix. We also propose the family Trueperaceae fam. nov. to accommodate this new genus.