The following thesis will describe the trajectory of a kite linked to the ground, with the purpose of producing wind power. The report will follow an usual technical structure that includes: introduction, state of the art, kite definition and requirements, mathematical model, code manual, results and conclusions. In the introduction chapter, the influence of renewable energies and in particular wind energy will be discussed, as well as, the technologies for its exploitation. Then, will be analysed the state of the art of the high-altitude wind power, because the kite of the thesis will work at high altitudes. When the setting in which the kite will produce wind power has been defined, the definition of the kite and the hypothesis on its movement will be commented in the chapter 3.