A Gram-stain-positive actinobacterium, designated strain SCSIO 15020(T), was isolated from sediment of the South China Sea, and characterized by using a polyphasic approach. The temperature range for growth was 24-60 °C, with optimal growth occurring at 50 °C. The pH range for growth was 6-10 (optimum pH 8-9). The NaCl concentration range for growth was 0-5 % (w/v). The peptidoglycan type was A4α. Polar lipids contained diphosphatidylglycerol, phosphatidylglycerol, phosphatidylinositol, phosphatidylinositol mannoside and an unknown polar lipid. The major menaquinone was MK-8(H4); MK-7(H4) was present as a minor component. The major fatty acids (>5 %) were anteiso-C15 : 0, iso-C15 : 0 and iso-C16 : 0. The DNA G+C content of strain SCSIO 15020(T) was 73.2 mol%. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain SCSIO 15020(T) belonged to the genus Georgenia, with the closest neighbours being Georgenia muralis 1A-C(T) (96.3 % similarity), Georgenia thermotolerans TT02-04(T) (95.7 %) and Georgenia ruanii YIM 004(T) (95.6 %). Based on evidence from the present polyphasic study, strain SCSIO 15020(T) is considered to represent a novel species of the genus Georgenia, for which the name Georgenia sediminis sp. nov. is proposed. The type strain is SCSIO 15020(T) ( = DSM 25884(T) = NBRC 108941(T)).