This paper shows the main results from a technical and economical study for the implementation of new cogeneration systems in Mexican refineries. At least three cogeneration alternatives to match a 50% additional energy requirement (thermal and electric) for a refinery are analyzed. A balance simulator tool developed specially for the electric and steam refinery systems is used in order to obtain the technical parameters for the alternatives, which allows obtaining system performance indicators such as fuel consumption, cooling water requirement, electric and combined efficiency. Standard techniques as net present value, internal rate of return, and payback period are used for the economic analysis. According to the results, the best alternative was a gas turbine-heat recovery steam generator arrangement fueled by natural gas, including the respective adjustments of the refinery electrical and steam systems.