A simulation model is developed and used to predict transient thermal behavior of the thermoelectric coolers. The present model amends the previous models. in which the P-N pair is simply treated as a single bulk material so that the temperature difference between the semiconductor elements was not possible to evaluate. Based oil the present simulation model, the thermoelectric cooler is divided into four major regions, namely, cold end (region 1), hot end (region 2), and the P-type and N-type thermoelectric elements (regions 3 and 4). Solutions for the three-dimensional temperature fields in the P-type and the N-type semiconductor elements and transient temperature variations in the cold and the hot ends have been carried out. The magnitude of the coefficient of performance (COP) of the thermoelectric cooler are calculated in wide ranges of physical and geometrical parameters To verify the numerical predictions, experiments have been conducted to measure the temperature variations of both the cold and the hot ends. Close agreement between the numerical and the experimental data of the temperature variations has been observed. (C) 2009 Elsevier Ltd All rights reserved.