A non-motile, yellow-pigmented bacterium, designated strain CW9(T), was isolated from a water-cooling system in Gwangyang, Republic of Korea. The cells were Gram-negative, catalase- and oxidase-positive, short rods. The major fatty acids were iso-C(15 : 0) (45.5 %), iso-C(17 : 1)omega9c (14.4 %), iso-C(17 : 0) 3-OH (13.0 %) and summed feature 3 (comprising iso-C(15 : 0) 2-OH and/or C(16 : 1)omega7c; 8.8 %). The DNA G+C content was 35.6 mol%. A phylogenetic tree based on 16S rRNA gene sequences showed that strain CW9(T) formed a lineage within the genus Chryseobacterium and was closely related to Chryseobacterium gleum ATCC 35910(T) (98.4 % sequence similarity) and Chryseobacterium indologenes ATCC 29897(T) (97.8 % sequence similarity). Phenotypic characteristics and DNA-DNA relatedness data served to distinguish strain CW9(T) from these two species. On the basis of the evidence presented in this study, strain CW9(T) represents a novel species of the genus Chryseobacterium, for which the name Chryseobacterium aquifrigidense sp. nov. is proposed. The type strain is CW9(T) (=KCTC 12894(T)=JCM 14756(T)).