In this study, a glucose-sensitive enzyme field-effect transistor (ENFET) coimmobilized with glucose oxidase (GOD) and manganese dioxide (MnO 2 ) have been investigated. The biomembrane of the ENFET was immobilized on the amorphous tin oxide/indium tin oxide glass structure extended sensitive gate, which used as a disposable transducer of a glucose biosensor. MnO 2 was used as a catalyst which can catalyze the hydrogen peroxide and produced H 2 O and O 2 . Coimmobilizaion of glucose oxidase and manganese dioxide was found to be useful for extending the dynamic measured range of glucose concentration to 360mg/dl (eq. 20mM). The result shows that the dynamic range of the output signal is strongly dependent on pH value of measuring environments, and the measurement in the alkali buffer solutions shows a higher response and wider dynamic range. Additionally, the different immobilized layers of MnO 2 have been studied. The MnO 2 , which be immobilized in outer cross-linking layer of bovine serum albumin, shows better results than immobilized in GOD layer or gultaraldehyde covalent layer.