Gas turbine engines are a vital part of today’s industry, providing both work and heat for several industry sectors, from transportation to cogeneration systems. The growing need for reliable electricity has encouraged the design of stationary gas turbines, including in Brazil, which operates on multiple fuels such as diesel, natural gas and low calorific fuels. To better monitor and control these engines, a complete analysis for prediction of transient operation is required. During transient operation of heavy duty gas turbines, the control system must keep the limits of certain parameters, such as turbine inlet temperature (TIT) and the rotational shaft speed within their design range. Moreover, the time required for the control system to react should be as short as possible to guarantee a safe and reliable operation. The turbine inlet temperature, which is a very important parameter in the performance of a gas turbine, is limited by the turbine blades material mechanical resistance. Furthermore, the rotational speed should remain constant due to the electric grid connection, which cannot withstand high frequency fluctuations. This work is motivated by the need to increase the ability of a computer model to simulate the performance of industrial gas turbines, incorporating, for this purpose, control system routines. As a result, the new model will be able to simulate any operating condition of industrial gas turbines, in both steady state and transient. The results obtained by the computer program proved to be faithful to the actual behavior of the engine. Furthermore, they showed the flexibility of the model to deal with different operating conditions. A computer program capable of simulating the transient performance of gas turbines is very important for the development softwares to help operators of such equipment. In addition, it could be used in on-line intelligent diagnostic program.