Abstract <p>The work is devoted to the determination of selenium(IV) content by anodic stripping voltammetry (<b>ASV</b>) with a gold rotating disk electrode (<b>GRDE</b>). The effect of the supporting electrolyte composition on the analytical signal (<b>AS</b>) of selenium is studied and the electrochemical characteristics (deposition potential, potential sweep rate, and deposition time) for recording the anodic current of selenium are optimized. The supporting electrolytes are 4 mM perchloric acid and 3 mM citric acid. A possibility of selenium determination by ASV using a GRDE in 3 mM citric acid is studied for the first time. The relative standard deviation for the concentrations of selenium 10 and 31 μg/L is no more than 5% for both electrolytes (<i>n</i> = 10). Although the sensitivity of the selenium AS in 4 mM perchloric acid is higher than that in 3 mM citric acid, the choice of citric acid as a supporting electrolyte offers a less toxic and more environmentally friendly alternative to perchloric acid. The limits of detection (<b>LOD</b>s) calculated using the 3<i>s</i>_<i>b</i>/<i>b</i> test are 0.05 μg/L in 4 mM perchloric acid (<i>t</i>_d = 60 s) and 0.1 μg/L in 3 mM citric acid (<i>t</i>_d = 90 s), while the limits of quantification (<b>LOQ</b>s) calculated using the 10<i>s</i>_<i>b</i>/<i>b</i> test are 0.15 and 0.3 μg/L, respectively. The method is applied to determine Se(IV) in a biologically active dietary supplement and in drinking water and demonstrates high accuracy (analytical recovery 96–108%) and rapidity.</p>