A glassy-carbon electrode was modified with cadmium pentacyanonitrosylferrate film using cyclic voltammetry. The voltammetry behavior of the cadmium pentacyanonitrosylferrate on the glassy-carbon electrode shows a redox couple (Fe(III)/Fe(II)) with E of 593 mV (I(pa)/I(pc) = 0.96) and Delta E(p), of 34 mV in 0.5 mol dm(-3) KNO(3) (nu = 100 mV s(-1)) with an adsorption-controlled process. The anodic-peak currents of the film decreased in the presence of tetrahydrothiophene clue to a reaction of the precipitation on the film surface by a nucleophilic attack. (C) 2011 Elsevier B.V. All rights reserved.