The superconducting properties of thin Sn films grown on an InSb(110) surfaces were investigated. The Sn phase formation is influenced by the substrate and is characterized by normal and superconducting Sn islands, which are electrically connected. The superconducting critical temperatures of the Sn films are lower than those of bulk Sn whereas the critical magnetic fields are larger. This behaviour can be understood based on the special morphology and phase formation of the films leading to a two-dimensional nature and an impact of the proximity effect.