Purpose: The work presents the application of the Finite Elements Method in a computer simulation whose aim is to determine the properties of PVD and CVD coatings on various substrates and to optimise parameters of a laser surface treatment process of surface layers of tool steels. Design/methodology/approach: The article discusses the application of the finite elements method for simulating the determination of stresses and microhardness of Ti+TiN, Ti+Ti(CN) and Ti+TiC coatings obtained in a magnetron PVD process on a substrate of sinter high-speed steel, of Ti/Ti(C,N)/CrN, Ti/Ti(C, N)/(Ti, Al)N, Ti/(Ti, Si)N/(Ti, Si)N, Cr/ CrN/CrN, Cr/CrN/TiN and Ti/DLC/DLC coatings obtained in a PVD and CVD process on magnesium alloys, of graded and monolayer coatings (Ti, Al)N, Ti(C,N) produced with the PVD arc technique on a substrate of sintered carbides, cermets and oxide tool ceramics and tool steel remelted and alloyed with a high-performance diode laser (HPDL). Modeling of stresses was performed with the help of finite element method in ANSYS and MARC environment, and the experimental values of stresses were determined based on the sin2Ψ. Findings: The models presented satisfy the assumed criteria, and they can be applied for the determination of properties of surface layers and optimisation of PVD and CVD processes and laser alloying and remelting. The results of a computer simulation correlate with experimental results. The models developed allow to largely eliminate costly, timeconsuming and specialist experiments which have to be done during investigations for the benefit of computer simulations. Research limitations/implications: To be able to assess the possibility of application of surface layers, a computer simulation of other properties of coatings has to be additionally carried out, and a strength analysis has to be made of other coatings coated onto various substrate materials. Originality/value: value Computer simulation and modelling is an interdisciplinary field necessary for the development of science and technology, enabling to perform direct visualisation of properties, which cannot be identified in experimental observations. The purpose of computer simulation and modelling is to improve the ability to predict results and to optimise solutions.