Tetragonal SnO compound was studied as the active electrode material in ＇Lithium-ion＇-type cell. Structural and Sn-119 Mossbauer properties of SnO are presented. The results concerning X-ray powder diffraction (XRD) and Sn-119 Mossbauer spectroscopy of lithiated crystallised tin oxide SnO between 0 and 2 lithium inserted per formula were reported. During the lithium insertion a reduction of SnO in beta-Sn and in an inter-metallic tin in strong interaction with the structural SnO (SnO --> beta-Sn and SnO --> Sn(0)) is observed. When the cell is recharged, the mechanism is in part reversible with the reformation of the SnO but there is also the formation of Sn(IV) (Sn(0) --> Sn(II) --> Sn(IV)).