The plant growth regulator 2-(1-naphthyl) acetamide (NAAm) is susceptible to degradation by sunlight and UV light in aqueous solution. Its inclusion complex with β-cyclodextrin (β-CD) was characterized by absorption and fluorescence spectroscopy and its photodegradation was compared with that of aqueous solutions of NAAm. The complex was formed with a stoichiometric ratio of 1:1 with a binding constant of 651 M−1. The photodegradation behavior of NAAm in the inclusion complex NAAm:β-CD was investigated using both UV (λ = 254 nm) and simulated solar light (Suntest) irradiation. It was found that the NAAm:β-CD complex increases NAAm photostability towards photochemical degradation markedly. In addition, an influence of β-CD concentration was also observed on NAAm degradation rate: higher β-CD concentrations lead to a slower photoinduced transformation. Moreover, some differences were found in the photoproducts in the presence and absence of the cyclodextrin, indicating inhibition of some of the mechanistic pathways. β-CD stabilizes NAAm photodegradation towards sunlight and UV irradiation, enhancing its efficient application on formulations for the treatment of fruits and vegetables. Journal of Inclusion Phenomena and Macrocyclic Chemistry Journal of Inclusion Phenomena and Macrocyclic Chemistry Look Inside Other actions Export citation Register for Journal Updates About This Journal Reprints and Permissions Add to Papers Share Share this content on Facebook Share this content on Twitter Share this content on LinkedIn