The electrochemical behaviour of the R-nitroso salt in 0.5MHAc/NaAc at pH 4.7 is studied by cyclic voltammetry. The compound shows a very sharp reduction peak at -0.37 V vs SCE giving the corresponding amine derivative. The height of the peak is shown to be inversely proportional to the iron (II) concentration of the solution. A linear calibration plot is obtained between 0 and 56 ppm of iron (II) using, initially, 4.0mMsolution of the salt. A simple and fast procedure was developed for the analysis of standard samples of ferrous iron.