A large expansion of the applicability of thermally sprayed coatings will be achieved, if there is success in tailoring the coatings structure. This is particularly necessary for functional coatings with special electrochemical or electromechanical properties. The coating structure is determined by the solidification of the sprayed particles on the substrate respectively the earlier deposited particles. In addition to the particle parameters - particle size, velocity, degree of melting and temperature of the melt, the substrate surface conditions - roughness, temperature, activity - influence the spreading and subsequently the solidification of the particles and the formation of the coating. Theoretical parameter studies show the particular influence of the above mentioned parameters on the coatings microstructure. The influence of the remelting of deposited particles caused by the following particles is regarded. The amount of remelted volume depends on the particle feed rate, particle size distribution, heat content and substrate temperature. By controlling these parameters even directionally solidified coatings can be produced. The calculations are in good agreement with the experiments.