Until recently cyanides were considered to be electrochemically non-reducible in aqueous solutions at mercury electrodes, but reducible at nickel, copper and silver electrodes. In our studies we noticed that the process is going on also at a renewable silver amalgam film electrode (Hg(Ag)FE). The electrochemical reduction of a novel fungicide with nitrile group, cyazofamid (Cfd) at the Hg(Ag)FE was studied for the first time. A rapid, sensitive, and new square-wave adsorptive stripping voltammetric (SWAdSV) method using a Hg(Ag)FE has been developed for the determination of Cfd. In order to understand the Cfd electrode mechanism, CV and SWAdSV techniques were applied. Cfd reduces at the Hg(Ag)FE with the cathodic signals being dependent on pH. The signal obtained at about -1.10V (citrate-phosphate (C-F) buffer, pH 2.6) was used for analytical purposes. Various parameters of the procedure, such as: pH, conditioning potential and time, frequency, amplitude, step potential, accumulation potential and time, were investigated. The developed SWAdSV method enabled Cfd determination in the concentration range of 4.00 x 10(-6)-2.00 x 10(-5) mol L-1. The procedure was successfully validated. The standard addition method was applied to determine Cfd in spiked Danube water and potato samples, and in the commercial formulation RANMAN Top. The effect of common interfering pesticides and heavy metal ions was also investigated. The adsorption of Cfd at the mercury electrode was studied. (C) 2014 Elsevier Ltd. All rights reserved.