The preparation and study of composite electroless nickel–phosphorus coatings with different sizes of diamond particles on a steel substrate, for use in including being used for special tooling parts, has been presented. The parts with the above dispersed coatings possess an abrasion resistance many times higher than those without diamond particles. Investigations on the influence of size of the particle (in the range 20–80 and 110 μm) on their inclusion and the thickness of the coatings have been carried out. The elemental composition and surface morphology were determined by microbe analysis in relation to the deposition kinetics. The problem of the adhesion of the coating to the substrate has been studied and overcome by an initial strike plating of nickel–phosphorus followed by nickel–phosphorus plating with included diamond particles. The electroless technology for deposition of nickel–phosphorus coatings dispersed with diamond powder on steel substrates for the production of diamond tooling instruments had been significantly developed in this study.