The tumor micro-environment is rich in glutathione. To exploit this feature for tumor-activatable porphyrin-based photosensitizers, a dimeric disulfide-bridged porphyrin has been designed and prepared, together with two reference derivatives, a non-cleavable dimer and a monomer. The three compounds have been investigated from a photochemical and photophysical point of view. It appears that the disulfide-bridged derivative exhibited intramolecular aggregation, but to an insufficient extent to induce a satisfying self-quenching of its photoproperties. Unlike expected, the non-cleavable dimer behaved like the monomeric derivative, due to the superior flexibility of the alkyl bridge over the disulfide bridge.