A method is described for sensitive and reliable determination of ultra-trace concentrations of antimony in environmental samples by anodic stripping potentiometry (ASP). The method involves potentiostatic deposition of antimony onto a glassy carbon mercury film electrode and the subsequent chemical oxidation (stripping) with mercury(II) ions. The optimum conditions for the reliable determination of antimony by this method are mixture of 1 M HCl and 0.5 M NaCl as supporting electrolyte, electrolysis potential of -400 mV vs. saturated calomel electrode (SCE) and 8 mg/1 of mercury(II) ions as oxidant. A linear concentration range is obtained from 0-250 μg/1 and the detection limit with a 10-min electrolysis time is 0.9 μg/1 (3% R.S.D., n = 6). The interferences of inorganic and organic substances such as lead, copper, cadmium, sodium dodecyl sulphate and Triton X-100 were overcome by selective deposition of the analyte and by the use of standard additions method. The use of a dry ashing procedure in conjunction with the anodic stripping potentiometric technique for the reliable determination of ultra-trace concentrations of antimony in environmental materials is demonstrated.