The photochemical reactions of 1,4-naphthoquinones included in alpha-, beta- and gamma -cyclodextrins (CDs) are studied using a time-resolved ESR method. The CIDEP (chemically induced dynamic electron polarization) spectra observed in the case of 1,4-naphthoquinone (NQ) in alpha- and gamma -CDs show the main formation of the NQ anion radical, contrary to the case of beta -CD that shows the naphthosemiquinone neutral radical. The carbon-centered radicals of the CDs are also identified in all the cases. The spin polarization patterns of these species prove that the reaction takes place via the excited triplet state of NQ, and the NQ neutral and anion radicals are ejected from the CD cavity. The initial reaction of these systems is the hydrogen abstraction from the CD framework and some NQ neutral radicals lose the proton to form the anion radical. In the case of 2-methyl-1,4-naphthoquinone in CDs, similar results are obtained. As for beta -CD both NQ and MNQ systems show the appearance of a broad emissive spectrum immediately after photolysis. This is tentatively assigned to a strongly coupled radical pair formed inside of the beta -CD cavity. Accordingly, the initial photochemical reaction takes place inside of the CD cavities and the NQ and MNQ radicals are ejected to the aqueous phase.