Hydrogenated amorphous carbon nitride (a-CN(x):H) materials were prepared using the radio-frequency (RF) magnetron discharge of the mixed gases of hydrocarbons and N(2). The starting hydrocarbons were CH(4), C(2)H(6), C(2)H(4), C(2)H(2), or C(6)H(6). The stored hydrogen contents of various a-CN(x):H materials formed from these starting hydrocarbons were measured by the volumetric analysis. The maximum hydrogen content, 0.78 wt.%, was obtained for the material formed from CH(4) at the equilibrium pressure of hydrogen of 11.3 MPa; the other materials gave much smaller hydrogen contents, 0.03-0.11 wt.%. The structures of a-CN(x):H materials were analyzed by IR and Raman spectroscopic methods and the near-edge X-ray absorption fine structure (NEXAFS) analysis of carbon K-edge. The correlation between the hydrogen-storage ability and the chemical structure of materials was discussed. (C) 2007 Elsevier B.V. All rights reserved.