In this study, an analysis has been carried out to determine the energy recovery capacity of a thermoelectric generator installed in the exhaust system of an internal combustion engine. The designed thermoelectric generator consists of an exchanger, twenty thermoelectric modules, and a cooling system. During the experimental tests, the engine has been operated under nine rotational speeds in the range of 3000 to 3800 rpm. The experimental results have demonstrated a 10.39% and 4.76% increase in exhaust gas temperature and mass flow. The temperature increase directly affects the power generated from the TEG, achieving a maximum recovery of 66.08 W. The power generated from the TEG increases by 31.58% with the change in engine rotational speed. The power recovered by the thermoelectric generator allows for improving the engine performance. The presence of the TEG has achieved a reduction of 2.06% and an increase of 2.01% in BSFC and thermal efficiency. At the maximum rotational speed condition, the implementation of TEG achieves a maximum engine efficiency of 32.08%. In general, thermoelectric generators are a viable way to recover part of the residual thermal energy from exhaust gases in different types of engines. However, their capacity is strongly associated with operating conditions such as rotational speed and engine load.