The trans→cis photoisomerisation of 3-cinnamoyl pyranone derivatives containing a central C=C bond was evaluated experimentally by UV/visible and fluorescence spectroscopy. Five different cinnamyol molecules in different solvents were irradiated to enforce a photochemical trans→cis isomerisation and the kinetics of the thermal back-reaction cis→trans were determined by UV/visible spectroscopy measurements in the temperature range from 298.15 to 313.15 K. This study aims to evaluate by UV/visible spectroscopy the effect of solvent polarity and the substituent in the aromatic ring on the percentage of conversion.