The superconducting oxides LnBa(2)Cu(3)O(7-x), (Ln = Y, Gd, Er, Yb, Lu) showed poor selectivity in the oxidative coupling of methane. The addition of 0.5 mol. % Li2O to these materials considerably enhanced the yield of C-2 hydrocarbons. This effect was related to both lower redox property and higher basicity of Li-doped catalysts as compared to those of undoped ones.