Strain H5T was isolated from a sediment sample collected from the coastal area of Qingdao, China. The cells were Gram-stain-positive, non-motile, straight or curved rods. The temperature range for growth was 20–37 °C and the pH for growth ranged from 6.5 to 9.0, with optimum growth occurring in the temperature range 28–30 °C and pH range 7.5–8.0. Growth occurred in the presence of 0–6 % (w/v) NaCl (optimum, 0–2 %). Strain H5T had MK-9, MK-9(H2) and MK-9(H4) as the major menaquinones and C18 : 1ω9c, C16 : 0, C14 : 0, C18 : 0 and C16 : 1ω9c as major fatty acids. The cell-wall peptidoglycan type was A5α l-Lys-l-Ala-l-Lys-d-Glu. The major polar lipids were phosphatidylglycerol (PG), an unknown phospholipid (PL1) and two unknown phosphoglycolipids (PGL1, PGL2). An unknown phospholipid (PL2) and two unknown glycolipids (GL1, GL2) were present in moderate to minor amounts in the polar lipid profile. The genomic DNA G+C content was 61.8 mol%. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain H5T represents a novel lineage in the family Actinomycetaceae . On the basis of phenotypic, physiological and molecular characteristics, it is proposed that the novel isolate should be classified as a novel species in a new genus: Flaviflexus huanghaiensis gen. nov., sp. nov., with strain H5T ( = DSM 24315T = CICC 10486T) as the type strain of the type species.