The critical temperatures (T(c)s) of superconducting oxocuprates are known to be correlated with the hole concentration. This can be in turn influenced by isomorphic substitution of cationic lattice constituents, the variation of the oxygen stoichiometry via thermal processes, or, as reported here, by reaction with hydrogen as the insertion of H should be equivalent to the extinction of a corresponding amount of holes. The reaction with hydrogen has been examined using in situ X-ray diffraction.