A novel bacterium, designated strain ARSA-15(T), was isolated from a freshwater sample collected from the Cheonho reservoir, Cheonan, Republic of Korea. The isolate was deep-yellow pigment, Gram-negative, rod-shaped, non-motile, and catalase- and oxidase-positive. Phylogenetic analysis based on 16S rRNA gene sequences showed that the isolate belongs to the genus Flavobacterium, and shared less than 97% sequence similarity with recognized Flavobacterium species. The novel species was able to grow at 10-37°C, pH 6.5-10.0, and in 0-0.5% (w/v) NaCl concentrations. Chemotaxonomically, iso-C(15:1), iso-C(15:0), and iso-C(16:0) were observed to be the predominant cellular fatty acid, and menaquinone-6 (MK-6) was the predominant respiratory quinone. The major polar lipid patterns of strain ARSA-19(T) was phosphatidylethanolamine, unknown aminolipid (AL1 and AL2), and unidentified polar lipids (L1, L2, and L3). The genomic DNA G+C content of the isolate was 39.2 mol%. On the basis of polyphasic approach, strain ARSA-15(T) represents a novel species of the genus Flavobacterium, for which the name Flavobacterium cheonhonense sp. nov. is proposed. The type strain is ARSA-15(T) (=KACC 14967(T) =KCTC 23180(T) =JCM 17064(T)).