The development of novel strategies for improving the efficiency of thermoelectric materials, along with an increasing global need for energy efficiency, has created a huge increase in thermoelectric research in the past two decades. At the same time, there has also been a rapid rise of the GaN, InN and AlN material systems due to their suitability for light emitting diodes, laser diodes, and power conversion devices. There remains however, remarkably little known about the thermoelectric properties of these III-Nitride materials. These materials have several important advantages in that they have good temperature stability, a wide bandgap, are non-toxic, and can take advantage of the developing infrastructure and knowledge base that is being driven by optical and power conversion devices. Initial experimental results show that these materials hold promise for high temperature thermoelectric energy generation, as well as integrated on-chip spot cooling applications and warrant significant investigation. The high temperature regime is particularly important because there are many heat sources, such as automobile exhaust, in this temperature range. In this report, current results for n-type GaN and InGaN are presented, with particular attention given to the effects of InGaN doping and composition. The doping of In<SUB>0.08</SUB>Ga<SUB>0.92</SUB>N material is shown to be an important optimization factor resulting in a peak power factor of 6.3e-4 W/mK<sup>2</SUP> at a doping of 1e19 cm<sup>-3</sup>. In addition, both the Seebeck Coefficient and electrical conductivity are shown to decrease with increasing Indium composition, making this another important optimization parameter, as thermal conductivity decreases with increasing Indium composition. Since the III-Nitride materials are expected to be most competitive in the high temperature regime, it is very important to measure the thermoelectric properties at the elevated temperatures in which they will be operating. To this end, the thermoelectric properties of GaN are measured and shown to improve through a temperature of at least 600 K. Finally, thermal conductivity measurements are currently under way with preliminary measurements of In<sub>0.14</sub>Ga<sub>0.86</sub>N showing a decrease in thermal conductivity from 140 W/mK for GaN to 5 W/mK, which results in an order of magnitude increase in ZT to near 0.05 at room temperature. In addition, a theoretical model based on the Boltzmann Transport Equation and the relaxation time approximation is presented in order to increase understanding and predict the relevant thermoelectric materials properties. This model is shown to have good agreement with experimental results. The rapidly growing industries based on III-Nitride materials, along with their promising thermal stability and emerging thermoelectric properties, make the III-nitride materials an important candidate for high temperature thermoelectric applications.