This paper presents an X-band single pole double throw (SPDT) switch build on a commercial 0.25 mu m Gallium Nitride (GaN) on silicon carbide (SiC) technology. Since the switch is designed to handle at least 25 W input power, special attention was given in minimizing the insertion loss, while achieving very high isolation values. This is achieved by utilizing carefully tuned double quarter wavelength transmission line architecture. The fabricated IC is measured to have 0.8 dB of insertion loss with peak isolation of 60 dB for the 8-12 GHz band, and reflections less than -10 dB throughout the whole bandwidth. The 1 dB compression point of the switch is measured at 43.3 dBm.