Single crystal of new nitrito bridged Mn(III) dinuclear compound {[Mn(L)(H2O)](μ-NO2)[Mn(L)(H2O)]}.(ClO4) has been synthesized in the absence of nitrite source. The compound was characterized by elemental analysis, IR spectroscopy and single crystal X‑ray diffraction. The compound crystallizes in the triclinic system in the space group P‑1 with a = 12.4175(3)Å, b = 13.6360(4) Å, c = 12.8207(5) Å, α = 74.876(3)°, β = 89.064(2)°, γ = 85.361(2)°, V = 2159.39(11) Å3, Z = 9, Dc = 1.489 Mg m-3. Each of the two ligand molecules encapsulates one Mn(III) ion in tetradentate fashion through two phenolate oxygen atoms and two azomethine nitrogen atoms. The two methoxy oxygen atoms of each ligand molecule remain uncoordinated. In the structure, each manganese(III) ion is situated in a N2O4 inner. The environment around each Mn(III) cation is best described as a distorted square pyramidal geometry, in which the equatorial plane is occupied by the atoms from the ligand molecule and the axial positions are occupied by one oxygen atom of a coordinated water molecule and one nitrito oxygen atom. The two Mn(III) ions are bridged though one μ1,3-nitrito group. Numerous intermolecular hydrogen bonds, established between water molecules as donors and phenoxo or methoxy oxygen atoms as acceptors, connect the dinuclear units into three-dimensional network.