This work proposes the development of a method to determine selectively and sensibly the environmental pollutant 1-chloro 2,4-dinitrobenzene (CDNB) by using a magnetic-sensor, which recognition material consist of modified magnetic nanoparticles with moleculary imprinted polymers (m-MIP) selective to CDNB, which is also electrochemically active, and will be of use for quantification applying electrochemical techniques such as cyclic or pulse voltammetry. The formation of the m-MIP electrode was made of a magnetized carbon electrode (m-CGE) and a heterogenic m-MIP CDNB solution with a glycine buffer, this solution was stirred by 2 hours for a better dispersion, then m-CGE was introduced by 20s to get the m-MIP electrode. The measures were done in a electrochemical cell of 3 electrodes containing Britton-Robinson buffer (pH 2) and ethanol in the proportion 9:1 (v/v), with a previous stage of pre-concentration by 15min at 60ºC. The selectivity of the sensor was evaluated with 8 different compounds, sensor detected p-dimethylaminoazobenzene, p-nitrobenzeneazoresorcinol y dinitrobenzene, obtaining equivalent currents 49.56%, 33.37% y 41.66% of analyte signal. Meaning that the sensor is highly selective. A lineal range between 4 and 50 mg L-1, adjusted with the lineal equation i (A) = (2.92 ± 0.05) x [CDNB] (mg.L-1) – (9 ± 1) . The repetibility of the flims were evaluated in five different days in function of RSD value, being equal to 2.7%, showing a recovery coefficient of 105.4% ± 3.7.