A Gram-stain-positive, spore-forming, rod-shaped, motile, strictly aerobic bacterium, designated CAU 1183(T), was isolated from marine sand and its taxonomic position was investigated by using a polyphasic approach. The bacterium grew optimally at 30 °C, at pH 8.5 and in the presence of 2% (w/v) NaCl. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain CAU 1183(T) formed a distinct lineage within the genus Oceanobacillus and exhibited the highest similarity to Oceanobacillus chungangensis CAU 1051(T) (97.6%). The strain contained MK-7 as the predominant isoprenoid quinone and anteiso-C15 : 0 was the major cellular fatty acid. The cell-wall peptidoglycan contained meso-diaminopimelic acid. The polar lipid pattern of strain CAU 1183(T) consisted of diphosphatidylglycerol, phosphatidylglycerol and unidentified lipids, including two phospholipids, two glycolipids, a phosphoglycolipid and two lipids. The G+C content of the genomic DNA was 37.5 mol%. On the basis of phenotypic, chemotaxonomic and phylogenetic data, strain CAU 1183(T) should be assigned to a novel species in the genus Oceanobacillus, for which the name Oceanobacillus arenosus sp. nov. is proposed. The type strain is CAU 1183(T) ( = KCTC 33037(T) = CECT 8560(T)).