A Gram-staining-negative and strictly aerobic bacterium, designated strain S2-A1T, was isolated from estuary sediment in South Korea. Cells of strain S2-A1T were oxidase- and catalase-positive rods without a gliding motility. Growth was observed at 15-40 °C (optimum, 37 °C), at pH 6.0-10.0 (optimum, pH 7.0-7.5) and in the presence of 0-4.0 % (w/v) NaCl (optimum, 0.5-1.0 %). The sole respiratory quinone was MK-7. iso-C15 : 0, summed feature 3 (comprising C16 : 1ω7c/C16 : 1ω6c) and summed feature 9 (comprising iso-C17 : 1ω9c/C16 : 0 10-methyl) were found as the major fatty acids (>5 % of the total fatty acids). The polar lipids of strain S2-A1T consisted of phosphatidylethanolamine, an unidentified aminophospholipid, three unidentified aminolipids and five unidentified lipids. The G+C content of the genomic DNA was 45.6 mol%. Strain S2-A1T was most closely related to Algoriphagus taeanensisHMC4223T with a 97.7 % 16S rRNA gene sequence similarity. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain S2-A1T formed a tight phyletic lineage with members of the genus Algoriphagus. On the basis of phenotypic, chemotaxonomic and molecular features, strain S2-A1T clearly represents a novel species of the genus Algoriphagus, for which the name Algoriphagus aestuariicola sp. nov. is proposed. The type strain is S2-A1T (=KACC 18987T=JCM 31546T).