The worldwide interest in thermoelectric waste heat recovery is constantly growing, with a wide range of applications ranging from small harvesters integrated into wireless sensor networks all the way to larger harvesters such as the ones that can potentially be integrated into cars. The wide range of applications makes a requirement for studying the dynamic response of TEGs. The aim of this work is to develop a mathematical model to accurately simulate the thermal and electrical behaviours of a longitudinal thermoelectric energy harvester (LTEH). In order to implement the theoretical analysis, a new TRNSYS component has been developed so this new model can also be used as a design tool. The LTEH model presented in this paper is validated through the comparison of results between theoretical analysis and experimental data. Testing results and discussion show the reasonability of this new model and also their use as a simulation tool. (C) 2014 Elsevier Ltd. All rights reserved.