High electron mobility, high current carrying capabilities, a relatively high thermal conductivity high temperature operation and a high breakdown field are the established key materials properties of GaN-based materials that make them competitive for high power applications. GaN-based devices have demonstrated high-temperature operation with little or no degradation up to 300 degreesC. The most spectacular results have been obtained for AlGaN/GaN microwave power High Electron Mobility Transistors (HEMTs) that yielded close to 10 W/mm Fewer at 10 GHz. The maximum density of the two-dimensional electron gas at the GaN/AlGaN heterointerface or in GaN/AlGaN quantum well structures can exceed 2x10(13) cm(-2), which is an order of magnitude higher than for traditional GaAs/AlGaAs heterostructures. Recently proposed Strain Energy Band Engineering technique should allow us to independently control of strain and lattice mismatch by using AlInGaN/GaN heterostructures and should find important applications in power devices. The prospects of GaN-based power device technology are also enhanced by a recent demonstration of high quality of GaN/SiO(2) interface. SiO(2)/AlGaInN/GaN Metal Oxide Semiconductor Field Effect Transistors have exhibited performance comparable or superior to that of conventional AlGaN/GaN devices and hold promise for power applications.