The HVOF process is the most attractive process used for fabricating WC-based coatings. These coatings have acquired an essential role due to their good properties against abrasive, erosive and sliding wear encountered in various industrial applications that range from mining, automotive, petroleum, aerospace to power generation industries. In addition, this process has been widely adopted for large size components because of its feasibility to cover large areas and effectivity to deposit the coating due to the high speed of the particles, allowing to obtain a coating with good cohesion, adhesion, and hardness. In this paper a computational simulation of a DJ2700 HVOF gun was carried out using hydrogen as fuel. Three process variables were analyzed in terms of their effect on the temperature and velocity of WC-Co-Cr particles, namely hydrogen flow, oxygen flow and oxyfuel flow and the input data for each variable was collected from the literature. A one-step chemical reaction model and the eddy dissipation model were used to numerically calculate the flame dynamics. To calculate the behavior of the particle a decoupling method was used. The results revealed that the hydrogen flow has the major effect on the temperature and velocity of the gases and, in turn, on particle temperature and velocity. On the other hand, the oxygen flow influences the pressure achieved inside the combustion chamber. In addition, the results revealed that the particle velocity is greatly influenced by the gas pressure in the combustion chamber, while the particle temperature is greatly influenced by the fuel/oxygen ratio.