Using the model proposed by Anderson and Yin and Chakravarty, the non-Fermi behavior of copper oxide superconductors has been analyzed using an energy dependent density of states of the Van Hove (logarithmic) form. The critical temperature degradation due to non-magnetic impurities has been analyzed. The values of critical temperature decrease with non-Fermi parameter α. The width D of the Van Hove singularity affects critical temperature. The larger value of D gives large value of critical temperature.