The complexation of pyrene by α-, β- and γ-cyclodextrins (CDs), persubstituted at the 6 position by tert-butyldimethylsilyl groups, has been investigated using steady state fluorescence spectroscopy. The α-CD derivative does not, as would be expected from steric considerations, form complexes. The β- and γ-CD derivatives form 1:1 host-guest complexes which show high association constants in 90:10 H 2O-DMF solution [i.e. β-CD(SiR) 7, 4.85 × 10 5 M -1; γ-CD(SiR) 8, 4.91 × 10 5 M -1]. Analysis of the polarity of the microenvironment by means of the I/III peak ratios shows a more polar cavity in the case of γ-CD(SiR) 8. The concentration dependence of I/III suggests that a weak supramolecular complex γ-CD(SiR) 8-pyrene-n·DMF, may exist.