A Gram-negative, non-motile bacterium, designated KSL5401-037(T), was isolated from a sewage treatment plant in Gwangju in the Republic of Korea and was characterized using a polyphasic taxonomic approach. Comparative 16S rRNA gene sequence analysis showed that strain KSL5401-037(T) belonged to the genus Acinetobacter in the family Moraxellaceae of the Gammaproteobacteria (Brisou and Prevot, 1954). According to a 16S rRNA gene sequence analysis, it was closely related to Acinetobacter johnsonii ATCC 17909(T) (97.3%), A. bouvetii 4B02(T) (97.2%), and A. beijerinckii 58a(T) (96.8%). Chemotaxonomic data revealed that strain KSL5401-037(T) possesses an ubiquinone system with Q-8 as the predominant compound and C(16:0) (19.2%), C(18:1) ω9c (19.5%), and summed feature 3 (C(16:1) ω6c / C(16:1) ω7c, 34.1%) as the predominant cellular fatty acids. The major polar lipids detected in strain KSL5401-037(T) were diphosphatidylglycerol (DPG) and, phosphatidylethanolamine (PE), followed by phosphatidylglycerol (PG) and moderate amounts of phosphatidylcholine and phosphatidylserine. The G+C content of the genomic DNA was 41.2-42.1 mol%. Strain KSL5401-037(T) exhibited relatively low levels of DNA-DNA relatedness with respect to A. johnsonii DSM 6963(T) (17.7%) and A. bouvetii 4B02(T) (9.3%). The DNA-DNA relatedness values, biochemical, and physiological characteristics of strain KSL5401-037(T) strongly support its genotypic and phenotypic differentiation from other recognized type strains of the genus Acinetobacter. Based on these data, strain KSL5401-037(T) (JCM 17071(T) =KEMC 5401-037(T)) should be classified in the genus Acinetobacter as a type strain of novel species, for which the name Acinetobacter kyonggiensis sp. nov. is proposed.