Deposition of carbonaceous films onto inner walls of small diameter tubes has been studied. A small size radio frequency plasma jet system with nozzles made from tungsten or graphite has been installed coaxially inside the tube. Changes in H-2 + CH4 (+O2) as compositions affected strongly the coating conditions on inner walls of the tube. The growth rate distributions of the microcrystalline primarily sp3 bonded film along the substrate area indicate an important role of the afterglow and peripheral regions of the plasma jet. Films were deposited onto Si, Mo, W, Cu, and Fe surfaces. At particular conditions incorporation of the substrate material into the growing films was observed. Contamination of films from the W nozzle was detectable only when oxygen was admixed in the working gas.