This paper presents polarographic (dc and differential pulse) and voltammetric (linear-sweep cyclic voltammetry) studies of the electroreduction of the s-triazine derivative 2,4-diamino-1,3,5-triazine on mercury electrodes. The studies are performed in the acidity range 2.25 M H2SO4 to pH 11. Above this last pH value no signals were obtained. In both dc DP polarography, two reduction waves/peaks were observed. The overall process corresponded to a two-electron irreversible reduction. For the first wave, the proposed reduction mechanism consists of the two-electron reduction of the reactant protonated in the heterocyclic N3 nitrogen, with reversible electron transfers. The rate-determining step (rds) is a protonation placed after such transfers. At pH values lower than the protonation pK, the protonation reaction takes place prior to the reduction. For the second wave, the unprotonated reactant is reduced and the rds is a protonation placed between the two reversible one-electron transfers. At high pH values, dissociation of the amino group causes the disappearance of the wave.