Abstract: A process and apparatus for the preparation and coating of the surface of a substrate by thermal projection, in which the surface of the substrate is progressively subjected to laser irradiation thereby at least partially to eliminate a superficial contaminating film on the surface of the substrate, and then there is projected by a thermal projection device a deposit material on the surface thus prepared immediately after the preparation. The surface of the substrate is subjected to successive laser and thermal projection treatments thereby to lay down on the surface a plurality of layers of deposit material. The substrate can be cylindrical, and can be rotated about its axis while continuously applying laser radiation and thermal projection thereto, with the substrate rotating in a direction such that the surface of the substrate is subjected first to laser radiation and subsequently to thermal projection. The laser is a pulsed laser.