A novel hepta-coordinated mononuclear manganese(II) complex, [Mn(L)(2)(H2O)](ClO4)(2)(.)2.5H(2)O [L = 1,2-bis(2'-pyridylmethyleneamino)propane], was obtained by assembly reaction of a di-Schiff base ligand L with manganese(II) perchlorate. The crystal structure shows that one of the L ligand acts as a quadridentate ligand, while the other one serves as a bidentate. The Mn(II) complex was found to have activity of dismutation of superoxide (O-2(-)) in the riboflavin-methioninenitro blue tetrazolium assay.