The title complex [Co-III{(naph)(2)dpt}(bzlan)]BPh4, where (naph)(2)dpt stands for bis-(2-hydroxy-1-naphthaldimine)-N-dipropylenetriamine dianion and bzlan for benzylamine, has been synthesized and characterized by elemental analyses, IR, UV-Vis and H-1 NMR spectroscopy. The structures of two possibly concomitant polymorphs, obtained from methanolic solution, [polymorph I (monoclinic, centrosymmetric, red-brown, thickish prismatic platelets) and polymorph II (orthorhombic, noncentrosymmetric, ochre olive-green, thin laths)] have been determined by X-ray crystallography. The geometry around the central cobalt ion is distorted octahedral in both polymorphs, but the benzylamine shows different kinds of orientation and disorder.