A moderately halophilic, Gram-positive, catalase- and oxidase-positive, rod-shaped, aerobic bacterium, designated strain JSM 071077T, was isolated from a subterranean brine sample collected from a salt mine in Hunan Province, China. Cells were motile by means of peritrichous flagella and formed ellipsoidal endospores lying in subterminal swollen sporangia. Strain JSM 071077T was able to grow with 2–25% (w/v) total salts (optimum, 5–10%), at pH 6.0–10.0 (optimum, pH 7.5) and 10–40°C (optimum, 25–30°C). meso-Diaminopimelic acid was present in the cell-wall peptidoglycan. The predominant menaquinone was MK-7, and the major cellular fatty acids were anteiso-C15:0, anteiso-C17:0 and iso-C15:0. The genomic DNA G+C content was 41.8 mol%. Phylogenetic analyses based on 16S rRNA gene sequence comparisons revealed that strain JSM 071077T should be assigned to the genus Halobacillus, being related most closely to the type strain of Halobacillus naozhouensis (98.8% sequence similarity), and the two strains formed a distinct subline in the neighbor-joining, minimum-evolution and maximum-parsimony phylogenetic trees. The sequence similarities between the novel isolate and the type strains of other recognized Halobacillus species ranged from 97.6% (with Halobacillus alkaliphilus) to 95.2% (with Halobacillus kuroshimensis). The results of the phylogenetic analyses, combined with DNA–DNA relatedness data, phenotypic characteristics and chemotaxonomic information, support that strain JSM 071077T represents a new species of the genus Halobacillus, for which the name Halobacillus hunanensis sp. nov. is proposed. The type strain is JSM 071077T (=DSM 21184T = KCTC 13235T).