A sensitive, selective and reproducible electrochemical method has been established for the electroanalysis of 4-nitroaniline (4-NA) using a carbon paste electrode modified with a chitosan solution gelled in acetic acid (CS@CPE). The modified electrode was then characterized spectroscopically using Fourier Transform Infrared (FTIR) spectroscopy. In addition, the electrochemical and interfacial characteristics of the as-prepared modified electrode were assessed by potentiodynamic cyclic voltammetry (CV) and AC electrochemical impedance spectroscopy (EIS). Differential pulse voltammetry (DPV) was additionally used to deduce the trace amounts of (4-NA) in phosphate buffered saline (PBS) of pH 7.0 as an ideal electrolyte. Under optimized conditions, the peak current of 4-NA increased linearly with the increasing 4-NA concentration over the range of 0.1 μM to 0.1 Mm. The calibration curve presents two linear ranges of current versus 4-NA concentration with a detection limit of 93.4 nM (3sb / B). The repeatability of the current peak registered at CS@CPE was performed at a level of 0.5 μM 4-NA employing one sensor on the same day for eight measurements. The relative standard deviation was 3.5%.