The studies of organic luminescent materials have been the focus of significant attention. Of particular interest are films grown from evaporable, small molecules such as tris(8-hydroxyquinoline) aluminum (Alq), which is a prototype used in organic light-emitting diodes (OLEDs), a promising innovation in flat-panel displays. At this time, there is no reported systematic method of synthesizing 8-hydroxyquinoline derivatives. We have found that a novel photochemical reaction of quinoline-5, 8-diones with aldehyde yields 8-hydroxyquinoline derivatives. In this reaction, four products are identified. They are one-to one addition product; 6-acyl-5, 8-dihydroxyquinoline, ester product; 8-hydroxy-5-acyloxyquinoline, one-to-two addition product, 6, 7-diacyl-5, 8-dihydroxyquinoline, and 5, 8-dihydroxyquinoline. The formation of one-to-one and ester products is explained by H-abstraction reaction from aldehyde by photoexcited quinoline-5, 8-diones, while the one-to-two addition product occurs as the result via multi steps including the redox process followed by another photochemical event.