Electrochemical oxidation of vanillin (VAN) in the presence of caffeine (CAF) was studied on a gold (Au) electrode modified with 3-amino-1,2,4-triazole-5-thiol (ATT) film by using differential pulse voltammetry (DPV) and cyclic voltammetry (CV) method. The formation of the ATT film on the Au electrode surface was characterized by the CV, fourier transform infrared spectroscopy (FTIR) and impedance spectroscopy (EIS) methods. A single irreversible oxidation peak of the VAN was obtained by using the CV method. The determination of VAN in the presence of CAF was carried out at pH 4 in Britton Robinson buffer (BR) by the DPV method. Under the optimal conditions, the oxidation peak current was proportional to the concentration of VAN in the range of 1.1 mu M to 76.4 mu M in the presence of CAF with the correlation coefficient of 0.997 and the detection limit of 0.19 mu M (S/N=3). The selective determination of VAN in a commercial coffee sample was carried out with satisfactory results on the ATT-Au modified electrode.