Pyran-2-one derivatives with functionalized azobenzene units were synthesized and their photochromic properties were studied by UV spectroscopy. UV/light irradiation of these heterocyclic Schiff bases at room temperature promotes the trans-cis photoisomerization of the N=N double bond to form variable amounts of the cis-isomer, leading to a remarkable change in the UV spectrum that, in the presence of visible light, returns thermally to the original form in a few minutes.