This paper is devoted to the investigation of the transient pressure occurring at the impact of a molten particle onto a flat substrate surface under different thermal spray conditions. In this paper, the mathematical model developed is based on the following assumptions: laminar, viscous and incompressible fluid; the mixed velocity-pressure model is employed to construct the finite element model. The choice of pressure penalty coefficient, which depends on the Reynolds number, is crucial for the results. This is discussed in this paper. The numerical results show that the pressure at the particle-substrate interface is strongly affected by the processing parameters, especially by the particle density and the impact velocity. The influence of spray parameters and material properties are also discussed.