Abstract: A great number of enzyme-catalyzed reactions are accompanied by heat evolutions.1 Therefore, flow-injection analysis (FIA) based on calorimetry, that is, flow-injection calorimetry,2,3 in combination with biocatalysts as specific recognition elements gives convenient and versatile analytical methods for biorelated compounds. Nakatani and Shimizu purified a thermostable laccase from Trametes sp. and reported its enzymatic properties recently.4 The enzyme functioned as the catalyst in oxidative reactions of various kinds of dihydroxylated compounds (so-called polyphenol compounds). We tried to apply its enzymatic properties to the determination of L-ascorbate in soft drinks. In this paper, we describe the fundamental performance of the calorimetric FIA system with use of the enzymes immobilized onto porous glass beads.