In low‐energy electron diffraction (LEED), we find two different reconstructions of the technologically important InP(001) surface, the well known (4×2) structure and a high temperature (4×2) structure with streaks at the half order spot positions which is interpreted as a disorderedc(8×2) structure. The corresponding electronic structures were investigated by ultraviolet photoelectron spectroscopy (UPS) and x‐ray photoelectron spectroscopy (XPS). For both types of reconstructions, we observe a surface state emission at the valence‐band maximum and a strong fermi‐level pinning. CaF2was deposited onto these surfaces, and the interface formation was studied by LEED, UPS, and XPS. The overlayer grows epitaxially with (001) orientation of its bulk fluorite structure inspite of the large lattice mismatch of 7.5%. The electronic interface scheme with its valence‐band discontinuity was deduced from photoemission measurements as a function of overlayer coverage. Band bending at the interface results fromp‐type defects.