The inclusion behaviour of β-cyclodextrin (β-CD) with felodipine (FL) as a guest molecule was studied. Inclusion complexes were obtained by the kneading method in a binary or ternary system with an addition of polyethylene glycol 6000. Formation of inclusion complexes was studied by IR spectroscopy, differential scanning calorimetry (DSC), and13C-NMR. It has been shown that an aromatic phenyl ring was involved in the process of complexation, and that in the solid clathrates the solubility of FL increased two fold when compared to the physical mixture, while it increased 10 fold in liquid three-component complexes. Moreover, the photochemical stability of felodipine was studied in its crystalline form and in the inclusion complexes with β-CD. Quantitative assessment of the felodipine photochemical decomposition was made on the basis of the rate constants of decomposition (k) in the first order kinetic reaction, half life time (t0.5) and the time of decomposition of 10% of the compound (t0.1). It was shown that complexation of FL with β-CD causes a two fold increase of the rate of the photodegradation process.