Nowadays with the depletion of fossil fuels and the ever-increasing climate change, the quest for renewable and “green” energy sources is getting more relevant every day. Thermoelectric generators are a helpful tool to improve energy yield. These generators can directly transform waste heat into electricity. These devices can be used to improve the efficiency of existing power sources or in any other situation where heat would be wasted. Nevertheless, the low efficiency of commercially available thermoelectric generators limits their applications. Theoretically, it has been predicted that nanowires can significantly increase the thermoelectric energy conversion because not only the thermal conductivity can be reduced without a loss of electrical conductivity, but also the power factor, is expected to be enhanced due to the modified density of states. In this thesis, the results of the experimental research of thermoelectric energy conversion in semiconductor nanowires are presented.