The title compound, [Mn(C(18)H(18)N(2)O(4))(C(7)H(5)O(3))(H(2)O)], was synthesized by a template reaction of ethane-1,2-diamine and 3-methoxy-salicylaldehyde in presence of manganese(II) 4-hydroxy-benzoate. The Jahn-Teller-distorted manganese(III) centre has an octa-hedral geometry. Extensive O-H⋯O hydrogen-bonding inter-actions generate a two-dimensional sheet structure parallel to (103).