Manganese(II) perchlorate reacts with L1=N,N,N'-tris(2-methylpyridyl)-N'-hydroxyethyl-ethylenodiamine and L2=N-(2-hydroxybenzyl)-N,N'-bis(2-methylpyridyl)-N'-hydroxyethyl-ethylenodiamine in ethanol to form the corresponding complexes [MnL1(H2O)](ClO4)(2) and [MnL2]ClO4. Both complexes crystallize in the monoclinic system and space group P 2(1)/n. In [MnL1(H2O)](2+) and [MnL2](+) the manganese(II) ion is heptacoordinated and hexacoordinated, respectively. FTIR, elemental analysis and conductance measurements were all in accordance with the molecular structures of [MnL1(H2O)](ClO4)(2) and [MnL2]ClO4. The ability of [MnL1(H2O)](ClO4)(2) and [MnL2]ClO4 to catalyze the oxidation of the dyes methyl orange and reactive orange 16 was studied in aqueous alkaline solution (carbonate/bicarbonate buffer). Both complexes were active catalysts promoting significant enhancement of dye solution decolorization in comparison to control reactions. (C) 2013 Elsevier B.V. All rights reserved.