The crystal structure of the title compound, [Mn(ClO4)(C10H8N2)(2)(H2O)]ClO4, contains monomeric [Mn(bipy)(2)(ClO4)(H2O)](+) cations (bipy is 2,2'-bipyridine) in which the Mn-II ion is surrounded by a pair of chelating bipy ligands [Mn-N 2.222(5)-2.228 (5) Angstrom], an aqua ligand [Mn-O 2.142(4) Angstrom] and a perchlorate ligand [Mn-O 2.289(5)Angstrom] in a distorted octahedral arrangement. Adjacent cations are linked into dimers by pairs of O ... O hydrogen bonds [O ... O 2.795 (7) Angstrom].