Two novel Gram-stain positive actinobacteria,designated PS-14-16T and RS-7-1, were isolated from the rhizosphere of a mangrove and sea sediment,respectively, and their taxonomic positions were investigated by a polyphasic approach. Both strains were observed to form vegetative hyphae in the early phase of growth but the hyphae eventually fragment into short rods to coccoid cells. The peptidoglycan type of both strains was found to be A4a. Their predominant menaquinone was identified as MK- 9(H4) and the major fatty acid as anteiso C15:0. The DNA G?C content was determined to be 68.4–68.5 mol persen. 16S rRNA gene sequencing revealed that strains PS-14-16T and RS-7-1 were related to members of the family Cellulomonadaceae.