A Gram-negative bacterium, designated B2-9(T), was isolated from water of a slightly alkaline lake, Longhu Lake in Daqing, north-east China. Strain B2-9(T) was an aerobic rod, heterotrophic, catalase- and oxidase-positive and motile by means of a single polar flflagellum. The isolate grew well on n-alkanes C(9)-C(17) and weakly on C(6)-C(8), C(18) and C(19). Growth occurred at 10-37 °C (optimum 20-25 °C), at pH 5.5-9.5 (optimum pH 7.0) and with ≤1.0 % (w/v) NaCl. The major fatty acids were C(18 : 1)ω7c (41.4 %), summed feature 3 (iso-C(15 : 0) 2-OH and/or C(16 : 1)ω7c; 18.5 %) and C(16 : 0) (10.9 %). Phylogenetic analyses based on 16S rRNA gene sequences revealed that strain B2-9(T) belonged to the genus Hydrocarboniphaga of the class Gammaproteobacteria and shared 97.0 % 16S rRNA gene sequence similarity with Hydrocarboniphaga effusa AP103(T). DNA-DNA relatedness between strain B2-9(T) and H. effusa DSM 16095(T) was 24 %. The DNA G+C content of strain B2-9(T) was 66 mol%. Strain B2-9(T) is considered to represent a novel species of the genus Hydrocarboniphaga, for which the name Hydrocarboniphaga daqingensis sp. nov. is proposed. The type strain is B2-9(T) (=CGMCC 1.7049(T) =NBRC 104238(T)).