A simple, inexpensive and highly sensitive electrochemical method for the detection of fenitrothion in tap water and human urine was developed using electrochemically pretreated glassy carbon electrode. Compared to untreated glassy carbon electrode, the electrochemically pretreated glassy carbon electrode showed a significantly enhanced peak current and peak potential shift indicating its catalytic activity towards fenitrothion reduction. Cyclic voltammetry was used to study the effect of pH, the dependence of peak current and peak potential on scan rate and to extract kinetic parameters (n, alpha, k(s), Gamma, E-0 and Delta E-pc,E-1/2). The peak current showed linear dependence on the concentration of fenitrothion with a linear regression equation, correlation coefficient (R-2) and limit of detection (LoD) of I-pc (mu A) = 0.796 C (mu M) - 0.043, R-2 = 0.9972 and 7.8 x 10(-8) M (S/N = 3), respectively. Recoveries in the range 933-96.7% from spiked tap water and 85.73-93.3% from human urine signified the applicability of the developed method for determination of fenitrothion in environmental samples. (C) 2012 Elsevier Ltd. All rights reserved.