This　paper　reports　the　photoinduced　chemiluminescence　(PCL)　of　a　methyl　cypridina　luciferin　analogue　(MCLA)　in　a　flow　injection　system　using　phthalocyanine　derivatives　as　photosensitizers.　The　photoexcited　phthalocyanine　produces　singlet　molecular　oxygen　(O-1(2))　in　air-saturated　solutions.　Subsequently　O-1(2)　reacts　with　MCLA　to　initiate　chemiluminescence.　The　MCLA-dependent　chemiluminescence　method　would　thus　potentially　provide　an　easy　way　for　determination　of　O-1(2).　Under　the　optimum　conditions,　the　increase　in　PCL　intensity　was　proportional　to　the　MCLA　concentration　ranging　from　0.1　to　1.0　mu　M.　The　assay　was　sensitive　and　reproducible　(the　relative　standard　deviation　was　6.3%,　n　=　10).　The　method　has　successfully　been　applied　to　compare　the　ability　of　O-1(2)　generation　of　tetra(potassium)　salt　and　tetra(tetrabutylammonium)　salt　of　tetra　sulfonated　phthalocyanine　zinc,　which　have　similar　structures　and　spectra.