This work presents the first observations of time-resolved photo-CIDNP in the dibenzyl-ketone-beta-cyclodextrin (DBK-beta-CD) inclusion complex. The photo-decay of the DBK-beta-CD inclusion complex gives a benzyl radical that is held in the beta-CD cavity for a time exceeding the time of its nuclear spin lattice relaxation. By estimating a change in the radical spin-lattice relaxation time in the complex, we determined that the rate constant of dissociation of beta-CD complex with the radical is less than or equal to10(5) s(-1). (C) 2003 Elsevier B.V. All rights reserved.