Thin films of YBa2Cu3Ox with superconducting critical temperatures (T,) ranging from 58 K to 72 K prepared by pulsed-laser deposition and subsequent irradiation with 75 key He ions. Optical the films with a He-Ne laser resulted in a small resistivity reduction, when the experiment was carried short period of time after the ion irradiation. The value of T, was essentially unchanged by the treatment. Further light excitation experiments did not show a significant effect on the resistivity samples. We conclude that ion-irradiated metallic YBa2Cu3Ox does not exhibit the persistent conductivity observed in oxygen-depleted samples with comparable critical temperatures. On the hand we have observed a long-term relaxation of T, towards larger values that takes place even when samples are kept in the dark. Our results indicate that T, may increase after ion irradiation to an value about 20% over the initial value on a typical time scale of years. This observation may be possible applications of light-ion irradiated YBa2Cu3Ox. (C) 2010 Elsevier B.V. All rights