Two bacterial strains (KMM 3633(T) and KMM 3634) were isolated from marine coastal sea-ice and characterized by using phenotypic and molecular methods. The isolates were aerobic, Gram-negative, psychrophilic, halophilic and motile by means of a single polar flagellum. The DNA G + C content was 45.3-45.6 mol%. The major cellular fatty acids were C(16 :0), C(16 : 1)omega9c and C(18 : 1)omega7c. Comparison of almost-complete 16S rDNA sequences demonstrated that the strains were phylogenetically closely related to each other (99.5% sequence identity), and related to Marinomonas species (94.4-96.4% identity). DNA-DNA reassociation between KMM 3633(T) and KMM 3634 occurred at a level of 92%. Based on phenotypic, chemotaxonomic and phylogenetic properties, the name Marinomonas primoryensis sp. nov. is proposed for strains KMM 3633(T) and KMM 3634; the type strain is KMM 3633(T) (= JCM 11775(T) = NRIC 523(T)).