In this paper trigeneration of power, heat and cooling is investigated. Trigeneration is the most environment friendly approach for efficient simultaneous production of power, heating and cooling. There are different layouts for trigeneration and depending on techno-economic specifications, the best combination should be chosen: there is no unique best trigeneration combination. Different trigeneration implementations and their characteristics are briefly explained in this paper, followed by an algorithm for choosing the best combination based on the overall system performance. Also, the practice to obtain the working conditions performance of trigeneration systems is outlined at the end.