Using a high-pressure technique, we have successfully synthesized (Ca(3)Al(2)O(5-y))(Fe(2)Pn(2)) (Pn = As and P), the first iron-based superconductors with the perovskite-based "32522" structure to be reported. The transition temperature (T(c)) is 30.2 K for Pn = As and 16.6 K for Pn = P. The emergence of superconductivity is ascribed to the small tetragonal a-axis lattice constant of the materials. From these results, an empirical relationship is established between the a-axis lattice constant and T(c) in iron-based superconductors, which offers a practical guideline for exploring new superconductors with higher T(c).