In the crystal structure of the title compound, [Mn(C5H7O2)2(C12H8N2)], the Mn2+cation is coordinated by one bidentate 1,10-phenanthroline ligand and two acetylacetonate anions within a slightly distorted N2O4octahedron. The asymmetric unit consists of one Mn2+cation situated on a twofold rotation axis, one half of a 1,10-phenanthroline ligand and one acetylacetonate anion. In comparison with the previous determination based on visually estimated intensities recorded on precession photographs, the current redetermination with image-plate data reveals bond lengths and angles with much higher precision.