A new method for differential pulse voltammetric determination of the priority pollutant 2,4,6-trinitrophenol (picric acid) on a bismuth bulk electrode using evaluation of the signal based on polynomial baseline fitting and subtraction is reported. Linear calibration curves were obtained in an acetate buffer (pH 4.0) solution from 2 × 10 −6 to 1 × 10 −4 mol L −1 of 2,4,6-trinitrophenol, with limits of detection and quantification of 2.0 × 10 −7 mol L −1 and 6.7 × 10 −7 mol L −1 , respectively. The newly developed method was tested on real sample matrices of drinking and river water.