A new species, Thuidium thermophilum Czernyadjeva, is described from thermal fields of the Kamchatka Peninsula (Russian Far East). Its diagnostic characters, description, illustrations, and differentiation from the other species of Thuidiaceae are provided. Thuidium thermophilum differs from all other Thuidium species in unipinnate branching, which suggests a closer relationship to Rauiella, but DNA analysis (nrITS and trnL-F) suggest closer relation to Thuidium.