The discogen bis[1,3-di(p-n-octylphenyl)propane-1,3-dionato]copper(II) crystallizes in two distinct morphologies, the more abundant needle-like form and the less abundant prismatic form. The crystal structure analysis of the first modification was reported in an earlier paper. Here we describe the structural details of the second modification. It belongs to the triclinic space group P1 with the copper atom lying on an inversion centre. The coordination around the metal atom is square planar and the octyl chains have an all-transconformation. The molecules stacked atop form a tilted columnar arrangement along the crystallographica-axis. The shortest metal-metal distance is 10.3Å which is very much larger than the value of 5.8Å observed in the needle-like form, and the molecules are more planar. The crystal and molecular structure of the prismatic form closely resemble that of the palladium complex, analyzed by us earlier.