A novel thermophilic actinomycete, designated strain 3-22-3, was isolated from mushroom compost collected in Nanning, Guangxi Province, China. The organism produced white aerial mycelium and short spore chains of non-motile oval spores with a ridged surface on the aerial mycelium. Strain 3-22-3 contained meso-diaminopimelic acid as the diagnostic diamino acid. The whole-cell sugars were galactose, glucose, madurose and ribose. Major fatty acids were iso-C17 : 0, iso-C16 : 0, iso-C15 : 0 and anteiso-C17 : 0. MK-9(H6) and MK-9(H4) were the predominant menaquinones. The polar lipids were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, phosphatidylinositol, phosphatidylinositol mannoside, ninhydrin-positive glycophospholipids, glycolipids and unidentified phospholipids. The G+C content of the genomic DNA was 72.5 mol%. The 16S rRNA gene sequence analysis indicated that strain 3-22-3 belonged to the genus Thermomonospora and showed the highest sequence similarity to Thermomonospora curvata DSM 43183 (96.3 %). On the 16S rRNA gene tree of closely related species and type species of all genera in the family Thermomonosporaceae, strain 3-22-3 formed a distinct phyletic line together with Thermomonospora curvata DSM 43183. Furthermore, the chemotaxonomic characteristics of strain 3-22-3 were congruent with the description of the genus Thermomonospora, but the morphological characteristics of strain 3-22-3 were significantly different from Thermomonosporacurvata. Based on the phenotypic and phylogenetic data, strain 3-22-3 represents a novel species of the genus Thermomonospora, and the name Thermomonospora catenispora sp. nov. is proposed. The type strain is 3-22-3 (=CGMCC 4.7155=DSM 46802=ATCC BAA-2627).