Cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and chronoamperometry (CA) techniques are essentially used for the study of the electroreduction of the two isomers maleic and fumaric acid systems in 0.1 M KCl at 298 K. The measurements are carried out on Pt nanoparticles electrodeposited on glassy carbon electrode (GCE). The modification of the electrode enables the appearance of better resolved peaks of the cyclic voltammograms of the two isomers of the acids in comparison with the poor behavior in absence of the modification. Two well-separated reversible cathodic waves at -0.44 and -0.59 V versus Ag/AgCl are characterizing the electroreduction cyclic voltammogram of maleic acid. The electroreduction of fumaric acid shows only one reversible peak at -0.362 V versus Ag/AgCl is observed. Peak separations and current functions together with other parameters of the electrochemical behavior of both isomers are calculated and discussed. Rate parameters of the anion radicals of both isomers in 0.1 M KCl on immobilized GCE with Pt nanoparticles are obtained and discussed.