An　HPLC　system　combining　a　chemiluminescence　detector　was　applied　to　estimate　the　singlet　oxygen　(O-1(2))　generation　ability　of　di-sulfonic　phthalocyanine　zinc　(ZnPcS2)　isomers.　As　photosensitizers,　ZnPcS2　produces　O-1(2)　in　air-saturated　solutions　under　photoirradiation.　The　latter　reacts　with　methyl　Cypridina　luciferin　analogue　(MCLA)　to　initiate　chemiluminescence.　This　photoinduced　chemiluminescence　(PCL)　of　MCLA　provides　an　easy　method　for　evaluating　the　isomers＇　O-1(2)　generation　ability　during　a　simultaneous　HPLC　separation　procedure.　The　cis-isomers　and　trans-isomers　of　ZnPcS2　show　different　O-1(2)　generation　abilities,　which　are　in　accordance　with　differences　in　their　absorption　spectra.　Copyright　(c)　2013　John　Wiley　&　Sons,　Ltd.