Theoretical study on oxygen deficiency for YBa2Cu3O7-δ high Tc materials has been carried out. The antibinding band on the Cu-0 plane is considered and critical temperature have been calculated for different oxygen contents by employing an anisotropic model for high Tc superconductivity. Calculations show 90k and 60k plateaus in Tc as a function of oxygen stoichiometry which agree with the recent experiments.
