An H2 dissociation model in the diamond deposition process is described and discussed using the results of a Monte Carlo computer simulation. A hot filament assisted chemical vapor deposition technique with substrate bias voltage was assumed and electron trajectories were computed. In this model, molecular hydrogen is dissociated by the impact of electrons accelerated towards the substrate. The number of dissociative collisions occurring while one electron flies from the hot filament to the substrate was calculated varying both the bias voltage and the gas pressure. The results we obtained here suggest that (1) the number of dissociations increases toward the biased substrate; (2) the production of H atoms generated in the gas phase is a function of the ratio of electric field to gas pressure, E/p; and (3) there is an optimum condition of E/p required to obtain efficient dissociation.