An unprecedented polynuclear cobalt complex with a [Co(24)] macrocycle in the presence of [Co(H(2)O)(6)](2+) has been prepared and characterized. In this complex, [Co(H(2)O)(6)](2+) not only acts as a counterion to balance the negative charge of the 2D layer, but may also serve as a template in the assembly of the [Co(24)] macrocyclic complex through hydrogen-bond interactions. Magnetic analyses indicate that the title compound shows homometallic ferrimagnetic behavior.