In this study, a sensor (2-TBA/PGE) for the sensitive, selective, cheap and rapid determination of 4-aminophenol (4AP) was easily prepared by depositing with 2-thiobarbituric acid (2-TBA) on a pencil graphite electrode (PGE) surface. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) methods as the electrochemical methods were used to characterize 2-TBA/PGE with using redox probe. The effective electroactive surface area of PGE (bare PGE, 0.030 cm2) increased about 6 times by coating with 2-TBA film on PGE (2-TBA/PGE, 0.174 cm2). This case caused that modified electrode exhibited a remarkable increment in the peak current of redox probe. Also, the sensor was characterized by Fourier transform infrared spectroscopy (FT-IR) was used to investigate the coupling sites of 2-TBA film and PGE surface. The oxidation peak current of 4AP on 2-TBA/PGE increased at about 6.81 times compared with the bare PGE. Under the optimized conditions, the anodic peak currents of 4AP were increased linearly with three concentration intervals of 4AP by using differential pulse voltammetry (DPV) technique. These intervals were found as 90 nM–0.5 μM, 0.5–9.46 μM and 9.46–423 μM. The limit of detection (LOD) was calculated as 21 nM. The determination of spiked 4AP in tap water, lake water and a child syrup containing paracetamol was successfully performed using the proposed method.