A novel Gram-negative, mesophilic, slightly halophilic, catalase- and oxidase-positive, obligately aerobic bacterium, designated strain YIM-C238T, was isolated from a sediment sample from a salt lake in the Qaidam Basin, north-west China. Cells were non-sporulating, non-motile, straight to slightly curved rods. Coccoid bodies and filaments of varying length developed in older cultures. Growth occurred with 0.5–6 % (w/v) NaCl [optimum, 2–3 % (w/v) NaCl], at pH 6.0–10.0 (optimum, pH 7.0–8.0) and at 10–40 °C (optimum, 25–30 °C). The major cellular fatty acids were anteiso-C15 : 0, 3-OH iso-C16 : 0 and anteiso-C15 : 1 ω10c, and menaquinone 6 was the sole respiratory quinone. Non-diffusible carotenoid pigments were produced. Flexirubin pigments were absent. The genomic DNA G+C content was 35.8 mol%. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain YIM-C238T should be assigned to the genus Psychroflexus. The sequence similarities between the isolate and the type strains of members of the genus Psychroflexus were in the range 95.5–97.0 %. The combination of phylogenetic analysis, DNA–DNA hybridization data, phenotypic characteristics and chemotaxonomic differences supported the view that strain YIM-C238T represents a novel species of the genus Psychroflexus, for which the name Psychroflexus sediminis sp. nov. is proposed. The type strain is YIM-C238T (=CCTCC AA 207030T=KCTC 22166T).