The calculation of the velocity of solid particles in the process of cold gas dynamic spraying is considered. The movement of the carrier gas in de Laval nozzle and in the space between the nozzle exit and the substrate surface is calculated by one-dimensional isentropic approach and by CFD method that comprising a solution of Euler and Reynolds Averaged navier-Stokes (RAnS) equations using a commercial package Ansys CFX. A system of ordinary differential equations for the parameters of the gas, particle velocity and temperature is obtained in one-dimensional non-isentropic approximation. For the particular case of air as a carrier gas and copper particles, the system of equations is solved by the Runge-Kutta method. For particles of different diameters, the particle velocity and the temperature were calculated at the nozzle exit both in the isentropic and non-isentropic approximations.