The effect of BeO substitution and addition in the superconducting properties of YBa2Cu3O7−&dgr;superconductors has been investigated by temperature resistance measurements and x‐ray diffraction studies. The results revealed that the substitution or addition of BeO in YBa2Cu3O7−&dgr;does not have much detrimental effect on the superconducting properties. Because of this nonpoisoning behavior, beryllia is suggested as a suitable substrate material for the production of superconducting thin films.