Thin films of SrF2, with a lattice parameter close to InP, have been grown by sublimation under vacuum on the semiconductor. This paper mainly deals with the electrical properties of the metal/polycrystalline SrF2 layers/n‐type InP (100) structures. For sweep rates greater than 10 Vs−1, the capacitance–voltage characteristics do not show any significant hysteresis. An important modulation of the surface potential of InP is observed. The surface state density, in the depletion and near the accumulation regions of the semiconductor is very low. For low‐voltage sweep frequencies a hysteresis occurs and is interpreted in terms of low‐ionic conductivity in the polycrystalline fluoride layers.