Two novel Rhodococcus strains, LHW50502T and LHW51113T, were isolated from marine sponges obtained on Xisha Island, Hainan Province, PR China. Rods and cocci, typical characteristics of the genus Rhodococcus , were observed. The strains contained meso-diaminopimelic acid as the diagnostic diamino acid in the cell-wall hydrolysates and galactose, arabinose, ribose and glucose as the whole-cell sugars. The major fatty acid identified was C16 : 0. MK-8(H4) was the predominat menaquinone of both strains. Stains LHW50502T and LHW51113T had almost identical (99.6 %) 16S rRNA gene sequences but shared relatively low similarities with previously characterized Rhodococcus species (well below 98.7 %). The results of phylogenetic analysis supported their closest relationship; however, the average nucleotide identity and digital DNA–DNA hybridization values between these two strains indicated that they belonged to distinct species. Taken together, the results of this study indicate that strains LHW50502T and LHW51113T represent two novel species of the genus Rhodococcus , for which the names Rhodococcus spongiicola sp. nov. (type strain LHW50502T=DSM 106291T=CCTCC AA 2018033T) and Rhodococcus xishaensis sp. nov. (type strain LHW51113T=DSM 106204T=CCTCC AA 2018034T) are proposed.