The diploma thesis deals with the optimization of purchasing process in the selection of suppliers in the company SUPPLY, s. r. o. In this work, we have focused on the theoretical analysis of management, purchasing and decision-making. In the following there were proposed methods and tools for application. In the chapter Results of the work we focus on streamlining and optimizing the decision-making process in selecting a supplier of sercer device in the chosen company by the application of pairwise comparison of selected criteria and subsequently the method of utility analysis and multi-criteria evaluation. The result of the thesis is to point out the shortcomings of the current state in the field of selection and evaluation of suppliers and to propose a solution by which this process could be optimized.