A taxonomic study was carried out on a novel bacterium, designated strain ck-I2-15(T), which was isolated from deep-sea sediment collected from the South-west Indian Ocean Ridge. Cells of strain ck-I2-15(T) were Gram-reaction-negative, rod-shaped, non-motile, moderately halophilic and capable of denitrification. Growth was observed with 0-9 % (w/v) NaCl and at temperatures of 10-37 °C. The novel strain was unable to degrade gelatin. The dominant cellular fatty acids were iso-C15 : 0, iso-C17 : 0 3-OH and summed feature 9 (iso-C17 : 1ω9c and/or 10-methyl C16 : 0). The major respiratory quinone was MK6 and the polar lipid profile comprised phosphatidylethanolamine, one unidentified phospholipid, two unidentified aminolipids, one unidentified glycolipid and four other unidentified lipids. The G+C content of the genomic DNA was 38 mol%. 16S rRNA gene sequence comparison indicated that strain ck-I2-15(T) was most closely related to Galbibacter mesophilus Mok-17(T) (92.9 % sequence similarity), followed by 'Joostella atrarenae' M1-2 (92.8 %), Joostella marina En5(T) (92.7 %) and Zhouia amylolytica HN-171(T) (91.6 %). Phylogenetic analyses based on 16S rRNA gene sequences showed that strain ck-I2-15(T) formed a clade with the genus Galbibacter, within the family Flavobacteriaceae. Several phenotypic properties allowed strain ck-I2-15(T) to be distinguished from its closest phylogenetic relatives. On the basis of the phenotypic and phylogenetic data, strain ck-I2-15(T) represents a novel species of the genus Galbibacter, for which the name Galbibacter marinus is proposed. The type strain is ck-I2-15(T) ( = CCTCC AB 209062(T) = LMG 25228(T) = MCCC 1A03044(T)).