The self-assembly process of a P-t(II)-linked hexagonal macrocycle consisting of six linear dinuclear Pt(II) units and six organic ditopic bent ligands was investigated.. The process Was monitored by H-1 NMR, and the intermediates in the self-assembly were analyzed by the n-k analysis. It was found that a, 1:2 complex of a dinuclear Pt(II) unit aria an organic, ditopic ligand was exclusively observed as an intermediate with a certain lifetime and that:the reaction of the 1:2 complex is the rate-determining step in the supramolecular macrocycle formation. The key 1:2 complex was unambiguously characterized by H-1 and DOSY NMR and ESI-TOF mass measurement.