Several wet etching solutions for AlGaP of different compositions have been studied. Al0.5Ga0.5P is found to etch in HF, H3PO4, hyphosphorous acid (HOPH2:O), HCl, KOH, and 1% Br-2-methanol (MeOH). Etching of Al0.5Ga0.5P in HCl is reaction limited with an activation energy of similar to 54.4 kJ/mol. At fixed conditions, the etch rates of AlxGa1-xP vary exponentially with x in HF and HCl, while in 1% Br-2-MeOH and mixtures of HCI and HNO3 the etch rates follow a linear dependence on AIP mole fraction. HF has been found to be a good etchant for AlGaP over InGaP or AlInP with high selectivity, while HCI is useful for the reverse case. The use of 1% Br-2-MeOH or the mixtures of HCl and HNO, provides little selectivity between AlGaP, InGaP, AlInP, and GaAs.