We found that methane was selectively oxidized by water to give Ct hydrocarbons and hydrogen on ATi(1-x)B(x)O(3-delta) (A = Sr, Ba, B = Mg, Ca). The coupling activity and selectivity on SrTi0.4Mg0.6O3-delta in the presence of steam was similar to 95%, which was much higher than that on pure SrTiO3. This suggests that the selective oxidative coupling of methane by water was catalyzed by the oxide ion defects on ATi(1-x)B(x)O(3-delta) (A = Sr, Ba, B = Mg, Ca).