Satellite structures have been observed adjacent to the main peaks in the X-ray photoelectron spectra of metal core levels, Ti(2p) and Fe(2p), as well as in the ligand core level, O(1s), of the surface oxides present on the FeTi alloys. These satellites have been interpreted in terms of charge transfer transitions (shake-up process). The satellites of the metal and ligand tend to be mutually exclusive, a behavior that can be understood on the basis of metal-ligand overlap; this behavior gives valuable clues to the nature of metal-ligand bonding. Based on these information, the deactivation and the difficulties involved in the reactivation of FeTi alloy toward better hydrogen sorption characteristics have been considered.