In the present work, nickel-samarium coatings (Ni-Sm) with 1.88% of samarium were obtained by electrodeposition from a nickel electrolyte composed of (NH 2 HSO 3 , Ni(CO 3 ) 2 and H 3 BO 3 ) and containing Sm 2 (SO 4 ) 3 . The electroactivity intervals of each component of the electrolytic bath and the effect of samarium (III) on the nickel electroplating process were studied by cyclic voltammetry and by electrochemical impedance spectroscopy (EIS). The results indicate that H 3 BO 3 and Sm 2 (SO 4 ) 3 added to the electrolytic bath are both reduced during the nickel electroplating. The Ni-Sm coatings were characterized using scanning electron microscopy (SEM), X-ray Diffraction (XRD), X-ray fluorescence (XRF) and X-ray photoelectron spectroscopy (XPS). The results indicate that the samarium species incorporated in the nickel coatings are found as Sm (III) Rare earth-transition metal alloys and nanocomposites have been attracting researcher's interest because of their excellent magnetic, hydrogen absorbing and catalytic properties. The incorporation of rare earth compounds into the coatings, especially of cerium oxide (CeO 2 ) into a nickel coating, has been shown to improve the wear, corrosion and oxidation resistance, as well as the hardness and catalytic properties.1-7 Electrodeposited Ni/CeO 2 nanocomposite coating showed improved microhardness, corrosion resistance and wear resistance when compared to Ni. 4 Samarium is another rare-earth element that, in close analogy with the behavior of cerium, also forms thin films capable of protecting the metallic substrates from corrosion attack. 8 Recently, Nickel coatings obtained by electrodeposition, from a sulfamate bath in the presence of Samarium (III), showed improved corrosion resistance. Usually, the incorporation of rare earth compounds into the coatings are obtained using an electrolytic bath, which contains rare earth nanoparticles or microparticles suspended in the electrolyte; these particles are embedded in the electroplated layer by applying an electrical current. Nevertheless, the possibility of obtaining a homogenous co-deposit of these particles in the matrix of Ni is very complicated and depends on many factors, such as particle size and distribution uniformity in the electrolyte.A new procedure for the creation of a Ni-CeO 2 composite coating was studied through the simultaneous electrodeposition of the metal and cerium oxide without the addition of CeO 2 particles in the electrolytic bath.10 Likewise, this procedure can be used for the incorporation of samarium compounds on Ni coatings. 9 Although studies have been reported on the deposition of rare earth and rare earth alloys produced by electroplating, the mechanism is not clear yet. 8,[10][11][12] The aim of this work was to study the role of the samarium (III) during the Ni electroplating on a Pt substrate from a sulfamate electrolyte. Electrochemical studies were carried out by cyclic voltammetry and electrochemical impedance spectroscopy (EIS). ExperimentalThe studies of nickel electrode...

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