The subject of this master thesis is euro currency in the Republic of Croatia and in countries of European Union. Through the paper, it is stated and explained how the Republic of Croatia approaches the Eurozone, and what conditions need to be met. Also, the member states of the European Union that have already introduced the euro and those that are still planning to do so, as well as the member states that are exempt from using the euro, were analyzed. The objectives of the research are: to state the importance of the function of the kuna's own currency in the Republic of Croatia, to present and briefly describe the processes and necessary criteria from Maastricht, i.e. the convergence of the introduction of the euro into the Republic of Croatia, and to explain the phenomenon of the introduction of the euro into the countries of the European Union, to determine and demonstrate the readiness of the Republic of Croatia to the euro currency through macroeconomic indicators and to analyze and present the state of individual European Union member states before and after the introduction of the euro currency. The master thesis "Euro currency in the Republic of Croatia and the countries in the European Union" consists of seven chapters, including an introduction, conclusion and literature. In the introductory part of the paper, the main subject and goal of the paper, as well as the set hypotheses, are stated. The second chapter provides general information about the kuna currency, the functions of the own currency and an explanation of the autonomy of one's own money. The third chapter is based on the euro currency, a brief overview of the European economic and monetary union is provided, which criteria must be met in order for a country to join the euro area. At the end of the third chapter, the phenomenon of the introduction of the euro in the countries of the European Union is briefly described and explained. The fourth chapter describes the state of the Republic of Croatia and readiness for the introduction of the euro through monetary policy and macroeconomic indicators. The fifth chapter analyzes the state of the European Union member states that have already introduced the euro and are still planning to, and the member states that are exempt from using the euro. At the end of the paper is a conclusion containing final considerations based on the previously researched data. The conclusion is followed by a list of professional literature used. The research methods used are: the method of comparison, description, analysis and synthesis.