A novel Gram-stain-negative, rod-shaped, non-motile strain, designated GKXT, was isolated from deep seawater. Strain GKXT was able to grow at 20-35 °C (optimum, 25 °C), pH 5.5-9.5 (optimum, 7.5) and 0-4.0 % (w/v) NaCl (optimum, 1.0 %). The major fatty acids were C16 : 1ω9c (15.4 %), C16 : 0 (18.4 %), C14 : 0 (12.0 %), iso-C14 : 0 (30.1 %) and anteiso-C15 : 0 (5.7 %). Strain GKXT contained phosphatidylethanolamine, phosphatidylmethylethanolamine, phosphatidylglycerol, diphosphatidylglycerol and an unidentified glycolipid as the main polar lipids. The only isoprenoid quinone was menaquinone-9. The diagnostic amino acids of the cell-wall peptidoglycan contained meso-diaminopimelic acid. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain GKXT belonged to the genus Luteolibacter in the family Verrucomicrobiaceae. The 16S rRNA gene sequence of this strain showed 98.0, 93.5 and 93.3 % sequence similarity, respectively, with those of Luteolibacter arcticus MC 3726T, L.uteolibacter pohnpeiensisA4T-83T and L.uteolibacter cuticulihirudinis E100T. DNA-DNA hybridization value of strain GKXT with L. arcticus MC 3726T was 33.1 %. The G+C content of the genomic DNA was 59.5 mol%. On the basis of the genotypic, phenotypic, phylogenetic and chemotaxonomic characteristics, strain GKXT was proposed to represent a novel species of the genus Luteolibacter, named Luteolibacter flavescens sp. nov. (type strain GKXT=MCCC 1K03193T=KCTC 52361T).