The supramolecular complex [Co(tn)(3)]PO4 center dot beta-CDX (tn = 1,3-diaminopropane; beta-CDX =,beta-cyclodextrin) was prepared through beta-CDX, rac-[Co(tn)(3)]Cl-3, and Na3PO4 in a mole ratio of 1:2:2. After one recrystallization process, the circular dichroism spectrum confirmed that complete enantioseparation of [Co(tn)(3)]PO4 is achieved in this system. X-ray crystal structure analysis reveals the presence of the only A-enantiomer in the unit cell and the head-to-head chiral discrimination structure of this system. Thus, we found that the present diastereomer formation with beta-CDX affords the very convenient and effective optical resolution procedure of [Co(tn)(3)](3+).