Green tea extract showed false-negative results in the determination of glucose via glucose oxidase (GOD) test. This investigation was undertaken to verify and find out the precise mechanism underlying this interference by determining the reaction kinetics of production and reduction of end-point chromophore. The peroxidase step of the GOD test was found to be interfered and phenols of the green tea were the interfering compounds. Green tea interfered and exerted its influence in a dual fashion. A part of the interference was observed as a result of the reduction of the finally formed chromophore, whereas the other form of interference was due to its hydrogen peroxide/free radical-scavenging activity. Reducing potential and the free radical-scavenging activity of the phenols in the green tea is the basis of the false-negative results of the glucose by GOD test. PRACTICAL APPLICATIONS Glucose oxidase test is a widely used test for the determination of glucose in research laboratories, and phenolic compounds, either from green tea or in pure form, are found to affect on its precision and accuracy. Interference target of green tea phenols is the reaction catalyzed by peroxidase enzyme which is also the part of many other diagnostic tests. Therefore, this study could be helpful to the researchers and clinicians to take cautions when using these types of tests in the presence of green tea especially and in the presence of other phenolic compounds in general.