DC-DC converters are highly considered in recent years because of the increased use of the renewable energy sources (RES). Since the energy output of the RES is depended on the weather conditions, DC-DC converters are used to regulate variable RES output. In this study, simulation based model predictive control (MPC) of a DC-DC buck converter is carried out. The performance of the designed controller is investigated under variable load condition and results are compared with PID controller. The transfer function of the converter model is used to design MPC controller in MATLAB/Simulink. MPC gives the better solution when it compared to PID controller under condition of constant load. The overshoot is not occurred when the predictive controller is used. PID provides better solution under the condition of load change whereas the overshoot is increased.