The title salt, C27H37N2+·ClO4−, arose as an unexpected oxidation product of the carbene 1,3-bis(2,6-diisopropylphenyl)-1,3-dihydro-2H-imidazol-2-ylidene in methanol. The five-membered cationic imidazolium ring is planar by symmetry and the complete cation is generated by a crystallographic twofold axis passing through the central N-bonded C atom and the mid-point of the C=C bond; the Cl atom of the perchlorate anion also lies on the rotation axis. The phenyl rings of the 2,6-diisopropylphenyl groups are each perpendicular to the imidazolium ring [dihedral angle = 90.0 (3)°]. In the crystal, weak C—H...O and bifurcated C—H...(O,O) interactions between the imidazolium ring H atoms and the perchlorate O atoms lead to [001] chains.