Clean GaP(001)‐(4×2) and H2S‐treated (1×2) surfaces are studied by scanning tunneling microscopy (STM). We have observed a (4×2)/c(8×2) STM image for the cation‐stabilized GaP(001) surface. The result suggests that the unit cell of the (4×2) structure consists of two Ga dimers with two missing Ga dimers. For the (1×2)S surface, the previous model that sulfur atoms are adsorbed on the Ga dimer and that a missing row of sulfur is formed along the [11¯0] direction is supported by the STM result. ©1995 American Institute of Physics.