The relative retardation of non-radiative rate and solvation dynamics of Nile Red (NR) in the nanocavity of cyclodextrins (CDs) (beta-cyclodextrin, beta-CD and gamma-cyclodextrin, gamma-CD) have been investigated by steady state and time resolved fluorescence spectroscopy. The non-radiative rate for twisted intramolecular charge transfer process is (TICT) retarded almost 2.5 times in presence of beta-CD whereas in presence of gamma-CD a little retardation of non-radiative rate compared to pure water is observed. We have observed time-dependent Stokes' shift of NR in aqueous solution of beta-CD but the same is not observed in case Of gamma-CD. The different feature of TICT and solvation of NR in two CDs (beta-CD and gamma-CD) arises due to the different types of complexation of NR with beta-CD and gamma-CD. (C) 2004 Elsevier B.V. All rights reserved.