Non-magnetic Zn2+, with varying molar concentration x (0 < x < 0. 1), is substituted in YBa2Cu3O7-delta at Cu(2) site. The samples are treated with deionised water for 16 h. The degradation effect on both the untreated and water treated YBa2Cu3-xZnxO7-delta samples is studied by employing temperature dependence resistance measurements, oxygen content and determination of unit cell parameters through X-ray diffraction. The results show that Zn2+ substitution, unlike the Sr2+ or the Al3+, does not control or prevent degradation of the superconducting samples rather it enhances with increasing concentration of zinc. (c) 2005 Elsevier B.V. All rights reserved.