A Gram-positive, spore-forming, rod-shaped, motile, strictly aerobic bacterium, designated CAU 1183T, was isolated from a marine sand and its taxonomic position was investigated using a polyphasic approach. The bacterium grew optimally at a temperature of 30C at pH 8.5 in the presence of 2% (w/v) NaCl. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain CAU 1183T formed a distinct lineage within the genus Oceanobacillus and exhibited the highest similarity to Oceanobacillus chungangensis (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 contains meso-diaminopimelic acid. The polar lipid pattern of strain CAU 1183T consisted of diphosphatidylglycerol, phosphatidylglycerol, and unidentified lipids including two phospholipids, two glycolipids, 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 1183T should be classified as a novel species in the genus Oceanobacillus, for which the name Oceanobacillus arenosus sp. nov. is proposed. The type strain is CAU 1183T (=KCTC 33037T, =CECT 8560T).