Tourism is integral part of modern business, and also part of green economy. Tourism spas must be seen as a major part of the tourism in the countries that are rich in spas. In this case it must be considered as tool of achieving important economic goals. The paper proposes an evaluation model based on TOPSIS, and ELECTRE mathematical methods to help the decision makers in selection of the optimal strategy for Gamzigrad spa development. AHP method is used as ancillary method to determine the weights of criteria. A real case study is used for determination of the development strategies, towards green economy.