The transient thermal behavior of an exoreversible thermodynamic model of an annular thermoelectric cooler has been studied by one-dimensional unsteady-state heat transfer analysis. Unlike the flat plate geometry of thermoelectric coolers, which have equal heat transfer area at their hot and cold sides, an annular thermoelectric cooler has a higher heat transfer area at its hot side than its cold side. The temperature variations with time at the hot and cold sides of an annular thermoelectric cooler have been predicted for different cooling loads, current flow, variable thermocouple length and with different heat transfer coefficients at its hot side. Finally, the transient thermal behavior of an annular thermoelectric cooler has been compared with a flat plate thermoelectric cooler. It was found that, for typical operating conditions with zero cooling load, the annular thermoelectric cooler can maintain a 2.3-K lower temperature than the flat thermoelectric cooler. It was also found that when the cooling load is 0.055 W/cm2 with the hot side heat transfer coefficient of 0.010 W/cm2 K, the coefficient of performance of the annular thermoelectric cooler is 2.32% higher than the flat thermoelectric cooler.