Photochromic reaction of long-chain spiropyran (SP) and spriroindolinonaphthooxazine (SNO) monolayers were investigated. The small residual values of the surface pressure observed on the kinetic curves of the SP monolayer and corresponding to the residual absorption at the absorption band of merocyanine (MC) may be explained by the formation of MC J aggregates. The dark pressure-area isotherms for SNO monolayers were obtained. The dark relaxation kinetics of the MC form in SNO monolayers and water solvents after UV irradiation may be treated according to simple first-order kinetics.