Photoelectrochemical etching of n-InAs (E(g) = 0.36 eV) is demonstrated. Although the concentration of thermally generated minority carriers and saturation current are high compared to larger bandgap semiconductors, photocurrent to dark current ratios as high as 4:1 were obtained at low temperature (2-degrees-C) and at potentials near the flatband potential. A surface film primarily composed of arsenic oxide was formed during oxidative decomposition of the semiconductor and plays a role in the rate of dissolution and in the current-voltage response. In 0.2M H2SO4, 6 electrons per InAs were involved in the oxidation dissolution, while only 4 electrons per InAs were found in 0.2M HCl because of the formation of In(I)-chloride species.