The objective of this investigation was to develop a procedure for cleaning InP, to study the electrochemistry of InP(100) surfaces, and to look at the possibility of electrochemical digital etching of InP. Wet etches included pretreatment with Br-2/CH3OH and HF solutions, which left trace amounts of C and O. UV ozone cleaning of InP gave similar results but left the surface with a phosphate layer. Ion bombardment and annealing of InP resulted in a clean, well-ordered surface with a (2 x 4) reconstruction. However, voltammetry studies of this surface, in various pH solutions, suggested the presence of some dispersed clusters of metallic In. Voltammetry in acid electrolytes, 10 mM HCl and 10 mM H2SO4, evidenced oxidation of the metallic In clusters at -0.6 V to form a "stable" surface with a (1 x 1) low-energy electron diffraction pattern. Reduction in the hydrogen evolution region, at pH 9, resulted in the dissolution of some P, probably as a phosphine species. This was supported by the appearance of small amounts of metallic In on the surface. Those results suggested that digital etching of InP may be possible. However, a more extensive investigation of P reduction showed it was not surface-limited, making it unsuitable for electrochemical digital etching. (c) 2005 The Electrochemical Society.