Wet chemical and plasma etch processes were developed for pattering Of of Sc2O3 films on GaN. Chlorine-based plasma chemistries produced a significant chemical enhancement of removal rate over pure Ar sputtering. The etching was anisotropic and did not significantly alter the surface composition of the SC2O3 films. Reaction-limited wet etching in the HNO3/HCl/HF system was investigated as a function of solution formulation and temperature. The activation energy for the wet etching ranged from 8 to 14 kcal/mol and the etching rates were independent of solution agitation.