Abstract: The sample is injected into a carrier stream of 2.5 M H2SO4 - 1% KBr and passes through a reaction coil (2 m x 0.58 mm) at 6 mL min-1. The cathodic voltammetric signal produced by reduction of Br at +0.30 V (vs. the SCE) is monitored with use of a vitreous-carbon electrode. Calibration graphs are rectilinear for 0.08 to 2 mM ClO- or -BrO-. To determine 0.05 to 0.7 mM NH3 or 0.05 to 0.376 mM N2H4, the sample solution is treated for 10 min with excess of BrO- in phosphate buffer solution of pH 9.8, and the unconsumed BrO- are determined by the proposed method; the relative errors are generally <5%.