A bacterial strain 5YN5-8T was isolated from peat layer on Yongneup in Korea. Cells of strain 5YN5-8T were strictly aerobic, Gram-negative, coccobacilli, non-spore forming, and non-motile. The isolate exhibited optimal growth at 28°C, pH 7.0, and 0-1% NaCl. Results of 16S rRNA gene sequence analyses indicated a close relationship of this isolate to Acinetobacter calcoaceticus (97.8% similarity for strain DSM 30006T). It also exhibited 94.4-97.8% 16S rRNA gene sequence similarities to the validly published Acinetobacter species. The value for DNA-DNA hybridization between strain 5YN5-8T and other members of the genus Acinetobacter ranged from 16 to 28%. Predominant cellular fatty acids were C18:1 ω9c, summed feature 4 containing C15:0 iso 2-OH and/or C16:1 ω7c, and C16:0. The DNA G+C content was 43.9 mol%. Phylogenetic, phenotypic, and chemotaxonomic data accumulated in this study revealed that the isolate could be classified in a novel species of the genus Acinetobacter. The name Acinetobacter brisouii sp. nov. is proposed for the novel species, with 5YN5-8T (=KACC 11602T =DSM 18516T) as the type strain.