The paper deals with a waveguide-coaxial microwave-frequency module capable of exciting a torch microwave discharge in air at the end of single-wire Goubau line. The properties of this discharge are described, as well as its possible uses for applying fine-structure films of refractory materials to substrates. The surface pattern of propagation of microwave energy along the single-wire line in the form of plasmon-polaritons is experimentally supported.