Abstract X-ray photoelectron spectroscopy has been used to investigate the interactions between Ti and bismuth-based superconductors. It is shown that Ti adatoms leach oxygen from the under-lyng superconductors, forming Ti-O bond on the surface. In the interface region, Cu-O and Bi-O bonds are destroyed, Cu2+ and Bi3+ are reduced to metallic atoms. The electronic structures of the superconductors are disrupted by the Ti adatoms. By using the standard four-probe method, it is found that after Ti deposition, the transition temperature of the thin film is 10K lower and the zero resistance can not be reached.