This paper is dedicated to the comparison of experimental and numerical results obtained on iron particles characteristics during plasma spraying. Each part of the spray process (particle injection, behavior of the particle in the plasma jet and coating formation) may be studied using appropriate diagnostic techniques. In the present work, on-line measurements of in-flight particle characteristics were performed using an optical diagnostic technique insuring a real time control of temperature, velocity and diameter of particles during the spray process. Besides, numerical results were obtained considering momentum and thermal exchanges between the plasma jet and particles using an Eulerian-Eulerian model. The evolution of velocity and temperature with the particle size given by in-situ measurements were then correlated to those obtained with the numerical code.