MOLECULAR complexation of fullerenes in host-guest complexes has the potential to afford efficient large-scale purification of fullerenes 1. This method would avoid the losses inherent in the chromatographic techniques currently in use, which arise from irreversible absorption on the stationary phase2. Several host-guest interactions have been reported for C60, including the formation of complexes with 1,4-hydroquinone3,4, azacrown compounds5, certain water-soluble macrocycles such as γ-cyclodextrin6-8, and complexation between C60 and an iridium phosphine in which pendant groups attached to a phosphorus atom form a cradle for an adjacent C60 molecule9. Other relevant studies are the inclusion of C60 into a microporous aluminophosphate10 and the formation of a charge-transfer complex between C60 and a thiafulvalene11. Here we show that both C60 and C70 will form discrete complexes with calixarenes, bowl-shaped macrocycles with hydrophobic cavities. Complexation of p-Bu'-calixarene with a mixture of the toluene extract of 'crude' fullerene soot, followed by a series of recrystallizations, affords >99.5% pure C6. Our approach could lead to a substantial reduction in the cost of purifying C60 and C70.