The reaction of the Mn(II) and [Fe(CN)(6)](3-) ions in the presence of morpholine at 90 °C yields a new cyanide-bridged three-dimensional (3D) assembly, showing a ferrimagnetic ordering, frequency-dependent ac susceptibility, and hysteresis loops below 14.8 K. In addition, our feasible route to rationally design and prepare this new molecule-based ferrimagnet promises to provide new 3D cyanide-bridged complexes in the future research.