The voltammetric behavior and determination of picloram, a member of a pyridine herbicide family, was for the first time investigated on a boron doped diamond film electrode using cyclic and differential pulse voltammetry. The influence of supporting electrolyte and scan rate on the current response of picloram was examined to select the optimum experimental conditions. It was found that picloram provided one well-shaped oxidation peak at very positive potential (+1.5 V vs. Ag/AgCl electrode) in strong acidic medium. At optimized differential pulse voltammetric parameters, the current response of picloram was proportionally linear in the concentration range from 0.5 to 48.07 mu mol L-1 and the low limit of detection of 70 nmol L-1 as well as good repeatability (relative standard deviation of 2.6% at 10 p,mol L-1 for n=11) were obtained on unmodified boron-doped diamond film electrode. The proposed method was successfully applied in analysis of environmental (tap and natural water) and biological (human urine) samples spiked with picloram with good accuracy (relative standard deviations less than 5% for all samples, n =5). By this way, the boron-doped diamond could introduce a green (environmentally acceptable) alternative to mercury electrodes for the monitoring of herbicides. (C) 2013 Elsevier Ltd. All rights reserved.