In the title compound, [Bi(C 20H 17N)(ClO 4)] or C 20H 17BiClNO 4, the Bi III ion assumes a distorted trigonal-bipyramidal geometry, with two C atoms and the electron lone pair of the Bi atom at the equatorial positions and an amine N atom and a perchlorate O atom at the apical positions. Weak inter-molecular C - H⋯O hydrogen bonding is present in the cr...