InP(100) surfaces were S passivated in S2Cl2, (NH4)2S and sulfide-containing Br2 solutions. After S2Cl2 treatments, observations using atomic force microscopy indicated that the sample surface was rougher than the as-received sample. Some residual oxide was also identified by Auger electron spectroscopy and x-ray photoelectron spectroscopy analysis. Treatment of InP(100) in (NH4)2S and Br2/MeOH solutions containing trace amounts of S2Cl2 and (NH4)2S significantly reduced the surface roughness of the as-received sample. These treated surfaces were also found to be free of oxide and S passivated. These solutions therefore effectively removed the native oxide leaving substrates approaching atomic flatness and subsequently passivated surfaces with sulfur from the solution.