An electrochemical method using linear sweep voltammetry techniques was developed to determine nitrite ion in aqueous solution in the presence of nitrate. Nitrite solutions exhibited a well-defined oxidation wave at +1.0V vs SCE at vitreous carbon, while no oxidation process was observed for nitrate solutions. The pH of the nitrite solutions varied from 2.37 to 5.60 and no change was observed in the Ep values, except for the pH 5.60 solution, where little change was verified. The potential also did not vary with change in the nitrite concentration in the 5.0 x 10−5to 7.0 x 10−4mol L−1range. Very good straight lines for plots of current versus nitrite concentration in the 7.0 x 10−5to 7.0 x 10−4mol L−1range were obtained; the correlation coefficient was never worse than 0.990. The nitrite determination was also performed in the presence of 1.0 x 10−3mol L−1of NO3−ions. The addition of NO3−did not change significantly the current values even when it was added in one hundred times molar excess.