A novel strain, designated No. 7T, was isolated from a sediment sample collected from the alkaline, saline Lake Elmenteita located in the Kenyan Rift Valley. The optimal growth for the strain was found to be at temperature 30–35 °C, at pH 8.0–12.0 in the presence of 7.0–10.0 % (w/v) NaCl. The strain was observed to form a light green beige abundant aerial mycelium on Horikoshi 1 agar and to have morphological and chemotaxonomic characteristics typical of members of the genus Streptomyces. The peptidoglycan was found to contain LL-diaminopimelic acid as the diamino acid, with no diagnostic sugars identified. The predominant menaquinone was identified as MK-9(H6). The main polar lipids were identified as diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylinositol and an unknown phospholipid. Cellular fatty acids were found to consist of saturated branched-chain acids with iso-C15:0, anteiso-C15:0, iso-C16:0 and anteiso-C17:0 acids predominating. The type strain had a genomic DNA G+C content of 72.8 mol% and formed a distinct phyletic line within the genus Streptomyces. Based on the chemotaxonomic results, 16S rRNA gene sequence analysis and the low DNA–DNA hybridization value with the type strain of Streptomyces calidiresistens, it is proposed that strain No. 7T (= DSM 42118 = CECT 8549) represents a novel species, Streptomyces alkaliphilus. The INSDC accession number for the 16S rRNA gene sequence of strain No. 7T is KF976730.