A marine bacterium, designated SCSIO 03483(T), was isolated from a marine sediment sample collected from the Nansha Islands in the South China Sea. The strain produced roundish colonies with diffusible yellow-coloured pigment on nutrient agar medium or marine agar 2216. Optimal growth occurred in the presence of 0-4 % (w/v) NaCl, at pH 7.0 and a temperature range of 28-37 °C. 16S rRNA gene sequence analysis indicated that the isolate belonged to the family Flavobacteriaceae and showed relatively high sequence similarity with Imtechella halotolerans K1(T) (92.7 %). Phylogenetic analysis based on nearly complete 16S rRNA gene sequences revealed that the isolate shared a lineage with members of the genera Imtechella, Joostella and Zhouia. Phospholipids were phosphatidylethanolamine, two unidentified aminolipids and three unknown polar lipids. The major respiratory quinone was MK-6 and the major fatty acids were iso-C15 : 0, iso-C17 : 0 3-OH and summed feature 3 (C16 : 1ω6c/C16 : 1ω7c). The DNA G+C content of strain SCSIO 03483(T) was 38.4 mol%. On the basis of phenotypic, chemotaxonomic and molecular data, strain SCSIO 03483(T) represents a novel species in a new genus in the family Flavobacteriaceae, for which the name Sinomicrobium oceani gen. nov., sp. nov. is proposed. The type strain of Sinobacterium oceani is SCSIO 03483(T) ( = KCTC 23994(T) = CGMCC 1.12145(T)).