Abstract: Solutions of 0.1 mM KIO3 - 0.42 M KBr and 1 M H2SO4, fed at 0.35 mL min-1, were blended and then mixed with a water stream (1.14 mL min-1) into which 20 µL samples were injected and fed via a 3.5-m reaction coil to an amperometric detector with a platinum-wire indicator electrode maintained at +0.6 V vs. a silver-tubing electrode. The system was calibrated by use of 0.1 to 1 mM hydrazine, and could then be used to determine hydrazine and L-ascorbic acid in the range 0.2 to 0.8 mM and L-cysteine in the range 0.2 to 0.6 mM; coefficient of variation were ~0.4 to 0.7%.