The major cytotoxic agent with most current photosensitizers used in photodynamic therapy (PDT) is widely believed to be singlet oxygen (¹O₂). Determination of the ¹O₂ quantum yields for porphyrin-based photosensitizers, including hematoporphyrin derivative (HiPorfin), hematoporphyrin monomethyl ether (HMME) and photocarcinorin (PsD-007) in air-saturated dimethylformamide (DMF) solutions were performed by the direct measurement of their near-infrared luminescence. In addition, ¹O₂ quencher sodium azide was employed to confirm the ¹O₂ generation from the investigated photosensitizers. The maximal ¹O₂ luminescence occurs at about 1280 nm with full width at half maximum of 30 nm. The ¹O₂ quantum yields were found to be 0.61 ± 0.03, 0.60 ± 0.02 and 0.59 ± 0.03 for HiPorfin, HMME and PsD-007, respectively. These results provide that these porphyrin-based photosensitizers produce ¹O₂ under irradiation, which is of significance for the study of their photodynamic action in PDT.