Thermal sprayed coatings are widely used to improve wear and corrosion behavior of metallic surfaces. The coating characteristics depend on the morphology, which can be designed and adjusted for special applications. Therefore the knowledge of the interaction of process parameters with the resulting structure plays a very important role in the optimization of coating processes. The implementation of mathematical models allows to foresee the coating characteristics and enhance quality and process efficiency as well. In this paper, a model of the vacuum plasma spray process is presented. Theoretical studies show the influence of process parameters on temperature and velocity within the plasma jet. Heating and acceleration of particles by the plasma and following the spreading, superposition, cooling and solidification of particles on the substrate are investigated. The resulting structure depends on plasma properties, injection conditions, particle parameters and substrate properties. Systematic studies show the effect of parameter variation on the particle properties, cooling and solidification behavior and subsequently on the coating structure.