A non-motile, rod-shaped, light-yellow-pigmented bacterium, designated strain WPCB159(T), was isolated from freshwater samples collected from the Woopo wetland in Korea. The cells were Gram-negative, aerobic and catalase- and oxidase-positive. The major fatty acids were C(16 : 1)omega7c (34.8 %), iso-C(15 : 0) (24.2 %) and C(16 : 0) (9.4 %). The DNA G+C content was 44 mol%. A phylogenetic tree based on 16S rRNA gene sequences showed that strain WPCB159(T) forms a lineage within the genus Dyadobacter (family 'Flexibacteraceae') and is closely related to Dyadobacter hamtensis HHS 11(T) (97.8 % sequence similarity) and to other members of the genus Dyadobacter (95.2-96.8 % sequence similarity). The phenotypic characteristics and DNA-DNA hybridization relatedness data indicate that strain WPCB159(T) should be distinguished from D. hamtensis HHS 11(T). On the basis of the evidence presented in this study, strain WPCB159(T) represents a novel species of the genus Dyadobacter, for which the name Dyadobacter koreensis sp. nov. is proposed. The type strain is WPCB159(T) (=KCTC 12537(T)=NBRC 101116(T)).