Our interest in Environmental Chemistry has prompted us to design new materials containing polyfunctional units able to bind certain metallic ions. These materials can be used as modifying agents to produce chemically modified electrodes. We expect to facilitate the detection of organic pollutants in water by binding these materials to an electrode surface. We report a Ni(II) and Co(II) complexes prepared from the Schiff base macroligand N,N´-bis(2-nitrobenzyl)ethylendiimine (L₁) with Ni(II) salt and L₁ with Co(II) salt. The nature of the complex was established by common spectroscopic techniques. A thermal gravimetric analysis of the complex showed that it is thermodynamically stable. Its formation constant was obtained by conductimetric analysis (K_f = 1.25x10⁶). The affinity of L towards Ni(II) and Co(II) was determined by atomic absorption. The electrochemical study of the complex [Ni(II)-L₁]SO₄ was also performed by the cyclic voltammetry technique. The results showed that, under certain conditions, this complex is capable of polymerizing on the electrode surfaces made of vitreous carbon and indium tin oxide. The chemical modification on the surface was probed by exploring the cyclic voltammograms, which showed oxidation and reduction peaks that are characteristic of the Ni(II)/Ni(III) pair. The sensing capability towards 2,4-dichlorophenol of these modified electrodes is currently under study.