The thesis describes testing process of device microwave oven according to international standard IEC 60335-1 and with second part IEC 60335-2-25. Introduction part presents the company SIQ Ljubljana and the meaning of standardization and standard. Thesis also describes operation microwave and basic requirements of standard household and similar electrical appliances according to IEC 60335-1. In the main section, there is a detailed description of tests of the microwave oven according to IEC 60335-2-25 and their results. The main part of the microwave test is based on testing of its construction and the leakage of its microwaves. The procedures of clauses are described and shown by the pictures, measurement tables and graphs.