A new bimetallic Schiff-base composite complex [Ni₂(LH₂)₂(H₂O)₂Cl₂][Mn₂Ni₂(LH)₄]₂Cl₄(CH₃OH) (1) has been synthesized by a simple one-pot reaction. The compound was structurally characterized by single-crystal X-ray diffraction. In the crystal structure the dinuclear nickel units are connected to the tetranuclear Mn₂Ni₂ units by means of strong hydrogen-bonding interactions. The compound was further characterized by ESI-MS, ligand-field and infrared spectroscopy. The magnetic properties of the compound have been studied in combination with preliminary DFT calculations, and have resulted in the successful determination of the nature of the magnetic exchange interactions between the metal ions, and hence the coupling constants.