The global energy and environmental issues are promoting the development of innovative energy solutions. Thermoelectric generators (TEGs) are regarded as a promising alternative to conventional energy technologies. TEG is a device that converts thermal energy directly into electric power by exploiting Seebeck effect. It is essential to understand the behavior of thermoelectric devices during both thermal transient and steady state to accurately simulate and design complex and dynamic thermoelectric systems. So a comprehensive model for simulating the dynamic TEG performance is developed, taking into consideration all the thermoelectric effects (Seebeck, Peltier and Thomson), in addition to Joule heating and Fourier heat conduction. Additionally, the effects of temperature-dependence of thermoelectric materials are accounted. Computational results are retrieved using “MATLAB" software. To verify the integrity of the modeling processes, the predicted results are compared with data obtained from the experimental evaluation. It is found that the outcomes of the experimental analysis validated the accuracy of the developed model and the possibility to be used as a simulation tool. The dynamic performance characteristics of a TEG is experimentally studied under different operating conditions. The effect of input heat rate and the influence of utilizing extended surfaces (fins) on both transient and steady state performance of a TEG are experimentally investigated. The variation in the temperature of the TEG hot and cold sides in addition to the output voltage is taken as a denotation of the performance characteristics. Input heat rate of 15.0 W, 17.5 W, 20.0 W, 22.0W and 25.0 W are applied to the TEG hot side. Free air convection is the utilized for heat dissipation from the TEG module through the cold side. From the experimentation, it can be deduced that increasing the input heat rate provides higher temperature difference across the module sides leading to higher power output. Additionally, using fins to aid heat dissipations enhanced the TEG performance by lowering the temperature of cold side and increasing the temperature difference across the module. The experimental data obtained are compared with the data available by the TEG module manufacturer and excellent agreement is obtained.