A Gram-negative, motile, rod-shaped bacterium, strain S4(T), was isolated from coastal sediment collected off Xiamen, China. The physiological and biochemical features of strain S4(T), determined using the API 20NE, API ZYM and Biolog GN2 systems, were similar to those of members of the genus Shewanella. Phylogenetic analyses based on 16S rRNA and gyrB gene sequences placed strain S4(T) in the genus Shewanella, and it was most closely related to Shewanella oneidensis and related species. DNA-DNA hybridization demonstrated only 11.9-30.4 % relatedness between S4(T) and the type strains of related Shewanella species. On the basis of phylogenetic and phenotypic characteristics, strain S4(T) is classified in the genus Shewanella as a representative of a distinct novel species, for which the name Shewanella xiamenensis sp. nov. is proposed. The type strain is S4(T) (=CCTCC M 209017(T) =JCM 16212(T)).