Controllable etching and surface passivation of InP semiconductors are desirable for removing damaged surfaces and obtaining good electronic properties. We have observed that organic acids (alpha-hydroxy acids: tartaric, lactic, citric, and malic), when used in conjunction with HCl to etch the (100) surface of InP results in smoother and defect-free surfaces, in comparison to etches based on inorganic acids alone. The chelating action of the organic acids aids in efficiently removing In from the surface, which leads to a very controllable etching. These chemical treatments have implications in controlling surface properties such as band bending and surface recombination velocity.