Hydrogenated amorphous silicon carbon nitride (a-SiCN:H) thin films were deposited by hot wire chemical vapor deposition (HWCVD) using SiH 4 , CH 4 , NH 3 and H 2 as precursors. The effects of the H 2 dilution on structural and chemical bonding of a-SiCN:H has been investigated by Raman and X-ray photoelectron spectroscopy (XPS). Increasing the H 2 flow rate in the precursor gas more carbon is introduced into the a-SiCN:H network resulting in decrease of silicon content in the film from 41at.% to 28.8at.% and sp 2 carbon cluster increases when H 2 flow rate is increased from 0 to 20sccm.