This work explores the structure and physical chemistry of hybrid materials formed by casting of carbon precursors (i.e., acrylonitrile, AN) in mesoporous MCM-41 type siliceous materials. After polymerization and carbonization hollow carbonaceous fibers were formed and these were impregnated with Ni and Mo salts, i.e., 2.8 atoms Mo/nm(2) and Ni/(Ni + Mo) ratio equal to 0.5. The supported metal carbides were characterized by XRD, BET, NH3-TPD and HRTEM and evaluated for the catalytic hydrocracking of intermediate straight chain model paraffins (i.e. n-octane) at 673 K, P = 1 atm. The overall activity and selectivity of the NiMoC/PAN-P catalysts for n-C-8 hydrocracking were distinct with respect to other catalysts of reference, i.e., NiMo/Al2O3, In particular, carbon nanofibers and lower hydrocarbons (i.e., from propane to n-heptane) are the products formed by the successive dehydrogenation, cracking and carbon atoms diffusion through the metal particles. Crown Copyright (C) 2009 Published by Elsevier B.V. All rights reserved.