The voltammeric behaviour of rimsulfuron herbicide has been studied by square wave stripping voltammetry on static hanging mercury drop electrode. It exhibited a well-defined peak within the pH range of 1.0-6.0, having a maximum peak response at -600mV (vs.Ag/AgCl) at pH 3.0. The factors such as accumulation potential (E-acc), accumulation time (t(acc)), frequency (f), pulse amplitude (Delta E) and step potential (Delta E-s) have been optimised. The calibration plot was a straight line in the range of 4.4-134.4 mu gL(-1) with a detection limit of 1.3 mu gL(-1). The validity of the method was assessed from the recoveries of spiked lake water, tomato juice and agrochemical formulation of Doncep((R)). The results of the experiments conducted for five recoveries were 48.8 +/- 1.7 and 49.7 +/- 1.0 mu gL(-1), which are very close to the rimsulfuron spiked to lake water and tomato juice (50 mu gL(-1)), with a relative error of -2.4% and -0.6%, respectively. The electrode reaction mechanism was also postulated.