Density functional calculations are used to investigate hydrogen (H) behaviors in vanadium carbide (VC). Molecular H-2 dissociation, atomic H diffusion and penetration are analyzed using the transition state theory. H-2 prefers to be close to the surface as physical adsorption, providing an environment conducive for further dissociation, and dissociates into atomic H adsorbed at the top C atom sites with co-adsorption state. The dissociation rate on the surface is mainly limited by the temperature-controlled activation energy barrier. The adsorptivity of atomic H by the surface tends to decrease as increasing of H coverage. For atomic H penetration through the surface, a significantly endothermic energy barrier and the low diffusion prefactor suggest that the main resistant effect of H permeation takes place at the surface. Energetic, vibrational, electronic consequences, and quantum effects on the H behaviors are discussed thoroughly. Our theoretical investigation indicates VC is a promising hydrogen permeation barrier. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.