A novel bacterium, strain L3T, was isolated from an activated sludge sample retrieved from a municipal wastewater treatment plant in Huangdao, China. On the basis of 16S rRNA gene sequence similarity studies, strain L3T was affiliated to the genus Sinorhodobacter, being most closely related to Sinorhodobacter ferrireducens (98.0 %). The 16S rRNA gene sequence similarity of strain L3T to other related species, Thioclava atlantica DLFJ1-1T (96.5 %), Rhodobacter capsulatus ATCC 11166T (96.3 %), Paenirhodobacter enshiensis DW2-9T (96.3 %) and Rhodobacter viridis JA737T (96.0 %) is less than 96.5 %. Chemotaxonomic characterization further supported classification of the strain to the genus Sinorhodobacter. The major polar lipid profile consists of diphosphatidyglycerol, phosphatidylglycerol and phosphatidylethanolamine. The major fatty acids are C18:1 ω7c (66.3 %), C16:0 (12.9 %) and C18:0 (8.0 %). The major quinone is Q-10. The G+C content of the genomic DNA of strain L3T is 68.0 mol %. DNA–DNA relatedness value between L3T and the closely related type strain S. ferrireducens SgZ-3T was 35.2 %. Based on these results, a new species Sinorhodobacter huangdaonensis is proposed. The type strain is L3T (= CGMCC 1.12963T = KCTC 42823T).