The ability to generate singlet molecular oxygen, O 2 ( 1 Δ g ), and the scavenging activity of two well-known 1,4-dihydropyridines (1,4-DHPs) such as nifedipine (1,4-dihydro-2,6-dimethyl-4-(2-nitrophenyl)-3,5-pyridine-dicarboxylic acid dimethyl ester) and nitrendipine (1,4-dihydro-2,6-dimethyl-4-(3-nitrophenyl)-3,5-pyridine-dicarboxylic acid ethyl methyl ester) is assessed.Results show that nifedipine does not generate O 2 ( 1 Δ g ) under our experimental conditions. In contrast, this 1,4-dihydropyridine behaves as a good scavenger of excited oxygen, mainly via physical deactivation with values of the total rate constant ranging from 20.8×10 5 M −1 s −1 in dioxane to 93.0×10 5 M −1 s −1 in propylencarbonate. The less favored reactive pathway generates a photooxidation product, which has been isolated and identified by GC–MS as the nitropyridine derivative. Voltammetric experiments also confirm the generation of this oxidation product.On the other hand, nitrendipine yields O 2 ( 1 Δ g ), but it is a less efficient scavenger of this species. Rate constants range from 1.88×10 5 M −1 s −1 in ethyl acetate to 15.8×10 5 M −1 s −1 in N,N-dimethylacetamide, the reactive channel being the main O 2 (Δ g ) deactivation pathway.Dependence on solvent microscopic parameters of the total rate constant for the reaction between singlet oxygen and 1,4-DHPs permits us to propose a mechanism involving a perepoxide-like encounter complex in the first step of the reaction path.