In an internal combustion engine, the temperature of the exhaust valve and its seat becomes extremely high as high temperature gases exit the engine. In order to avoid damage of the exhaust valve, the rate of the heat transferred from it should be under control. As the significant amount of the heat transfers when the exhaust valve is in contact with its seat, the estimation of thermal contact conductance and the identification of the parameters which have influence upon it are one of the most considerable challenges in the design of an internal combustion engine. In this paper, the thermal contact conductance is estimated by using the temperatures measured at several points within the exhaust valve and its seat. The linear extrapolation and inverse methods are applied. The results show that the thermal contact conductance increases as the contact pressure rises. In addition, a numerical simulation of the problem is performed by using a commercial software package. The thermal contact conductance obtained by inverse method is utilized as an input to the analysis. The temperatures obtained at thermocouple locations are compared with measured temperatures in order to validate the inverse solution and to investigate the accuracy of the numerical solution using the software. The error associated with numerical solution is larger than those due to two other methods. Generally, numerical results cover the measured temperatures and are acceptable.