A new modified electrode (5AT2T-Au) was prepared by electrochemical deposition of 5-amino-1,3,4-thiadiazol-2-thiol (5AT2T) on the gold electrode (Au) surface to determine 4-aminophenol (4AP). First, the type and pH of the supporting electrolyte and voltammetric technique suitable for the determination of 4AP were optimized. Response surface methodology (RSM) experimental design was used to achieve better analytical performance with the 5AT2T-Au sensor used. For this purpose, the effect of the combination of frequency (f), square wave amplitude (delta Esw) and potential step (delta Es) parameters of the square wave voltammetry technique (SWV) on the anodic peak current of the 4AP was investigated. Under the optimum parameter combination, for the deter-mination of 4AP with the 5AT2T-Au electrode, the limit of detection (LOD) value was found as 2.82 nM, and the working range was obtained as two linear concentrations ranges 9.9 nM-2.24 mu M and 2.24 mu M-1.84 mM. The determination of 4AP in drinking water, children's syrup, and milk samples on the proposed sensor with satis-factory results were successfully applied.