A mesophilic, endophytic, filamentous bacterium, designated strain NEAU-gxj18T, was isolated from soybean root [Glycine max (L.) Merr.] collected from Harbin, Heilongjiang Province, China and characterized using a polyphasic approach. Growth was observed at 20–40 °C (optimum 37 °C). Aerial mycelium was absent on all the media tested. Substrate mycelia were well-developed and formed abundant single endospores with smooth surfaces. The only menaquinone was MK-7.The diagnostic diamino acid was meso-diaminopimelic acid. The whole-cell sugars were ribose, glucose and galactose. The major fatty acids were iso-C15 : 0, C13 : 0 and iso-C17 : 0. The polar lipid profile consisted of diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylethanolamine, phosphatidylglycerol, one unidentified aminophospholipid and one undientified phospholipid. The DNA G+C content was 49.9 mol%. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain NEAU-gxj18T was phylogenetically related to members of the family Thermoactinomycetaceae, with the highest sequence similarity to Geothermomicrobium terrae YIM 77562T (93.35 %). On the basis of morphological and chemotaxonomic characteristics, phylogenetic analysis and characteristic patterns of 16S rRNA gene signature nucleotides, strain NEAU-gxj18T represents a novel species of a new genus within the family Thermoactinomycetaceae, for which the name Baia soyae gen. nov., sp. nov. is proposed. The type strain of the type species is NEAU-gxj18T ( = CGMCC 4.7223T = DSM 46831T).