Wet chemical etching of A1N and InxAl1-xN was investigated in KOH-based solutions as a function of etch temperature, and material quality. The etch rates for both materials increased with increasing etch temperatures, which was varied from 20 °C to 80 °C. The crystal quality of A1N prepared by reactive sputtering was improved by rapid thermal annealing at temperatures to 1100 °C with a decreased wet etch rate of the material measured with increasing anneal temperature. The etch rate decreased approximately an order of magnitude at 80 °C etch temperature after a 1100 °C anneal. The etch rate for In0.19Al0.81N grown by Metal Organic Molecular Beam Epitaxy was approximately three times higher for material on Si than on GaAs. This corresponds to the superior crystalline quality of the material grown on GaAs. Etching of InxAl1-xN was also examined as a function of In composition. The etch rate initially increased as the In composition changed from 0 to 36%, and then decreased to 0 Å/min for InN. The activation energy for these etches is very low, 2.0 ± 0.5 kcal•mol-1 for the sputtered A1N. The activation energies for InAIN were dependent on In composition and were in the range 2–6 kcal mol-1. GaN and InN layers did not show any etching in KOH at temperatures up to 80 °C.