Water jet cutting technology (hydro-erosion) presents as unique, for future-oriented technology, with the high possibility of the introduction of automation for high-power cutting for actually all types of materials.The aim of the way was to find the definition of cutting parameters of water jet, which will guarantee technological and economical aspects. This process is associated with extensive utilisation of mathematical methods, using of computational procedures for specific tasks and at the utilisation of methodology of mathematics for methods of formulating solutions.