The tin sulfide film, formed by potentiostatic anodic polarization of tin in aqueous electrolyte containing sulfide ions, was investigated using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), X-ray photoelectron spectroscopy (XPS) and diffuse reflectance spectroscopy (DRS). According to XPS and Mott-Schottky (MS) tests, the surface film exhibits semiconducting properties and bilayer structure with the inner of Sn(II) sulfide layer of p-type conductivity and the outer layer of Sn(IV) sulfide layer of n-type conductivity. The film's electronic structure was discussed on the basis of band structure models, potential distribution at the interface and the availability of free charge carriers on the electrode|solution interface. The electronic structure of the passive film on tin influences its susceptibility to the oxidative as well as to the reductive solid-state decomposition. The semiconducting parameters of the sulfide film: the flatband potential, E-FB, the donor concentration, N-D and the optical bandgap, E-g were determined. (C) 2017 The Electrochemical Society. All rights reserved.