Abstract: The electrode was prepared by immersing a polished Pt electrode in stirred 1.0 M H2SO4 containing 0.1 M aniline and scanning three complete cycles between -0.2 and +1.1 V vs. a Ag - AgCl reference electrode at 20 mV s-1. Cyclic voltammetry (details given) in 0.2 M Na acetate buffer (pH 6.0) containing 0.1 M ClO4- or flow injection analysis of the same medium or one containing 0.2 M glycine, with detection at 0.2 or 0.5 V, respectively, gave best results for NO3-, Cl-, SO42-, Br-, NO2- and ClO4-, e.g., the calibration graph for flow injection analysis of NO3- was rectilinear over three orders of magnitude, and the detection limit was ~0.1 ppm with use of the glycine mobile phase.