A Gram-negative, rod-shaped, non-motile bacterial strain, designated JS12-13(T), was isolated from soil from Halla Mountain on Jeju Island, Korea. Analysis of the 16S rRNA gene sequence of strain JS12-13(T) revealed that it was a member of the genus Polaromonas, sharing 96.9-98.4 % sequence similarity with type strains of the genus Polaromonas and being most closely related to Polaromonas aquatica CIP 108776(T). The major fatty acids of strain JS12-13(T) were summed feature 3 (C(16 : 1)omega7c and/or iso-C(15 : 0) 2-OH; 38.3 %), C(16 : 0) (28.4 %), C(17 : 0) cyclo (15.9 %) and C(18 : 1)omega7c (9.1 %). The major quinone found was ubiquinone-8. The G+C content of the genomic DNA of strain JS12-13(T) was 63.7 mol%. On the basis of phenotypic and genotypic characteristics, strain JS12-13(T) represents a novel species of the genus Polaromonas, for which the name Polaromonas jejuensis sp. nov. is proposed. The type strain is JS12-13(T) (=KACC 12508(T) =DSM 19351(T)).