Photophysical processes and photochemical reactions of a 15-crown-5-containing styryl dye of the pyridine series and its complexes with barium perchlorate in water in the absence and in the presence of cucurbit[7,8]urils were studied using absorption, luminescence, and laser kinetic spectroscopy. The trans—cis-photoisomerization, interconversion of the dye to the triplet state, and charge transfer were concluded to occur. The formation of a dye inclusion complex with cucurbit[7,8]urils was established.