La-Simetallic coatings with La/Si ratios between 1.55 and 1.66 weresynthesized by Direct Current Magnetron Sputtering of lanthanum and silicontargets in pure argon atmosphere. After the deposition stage, theceramic apatite-structure coatings were obtained by thermal oxidation in airfor 2 hours at 1173 K. The structural and chemicalfeatures of these films have been assessed by X-Ray Diffraction(XRD) and Scanning Electron Microscopy (SEM) equipped with Energy DispersiveSpectroscopy (EDS). The electrical properties were determined by Complex ImpedanceSpectroscopy in planar configuration. The films with near apatite structureLa/Si atomic ratio in range of La₁₀Si₆0₂₇ and La_9.33Si₆0₂₆ depositedon different substrates were initially amorphous. After thermal oxidation at1173 K in air, the coating crystallised under the expectedapatite structure. SEM observation revealed that the film compactness andthickness increased after thermal oxidation. The film adhesion on SOFCsmaterial is guaranteed if the anode support was not reducedbefore the deposition stage. A specific method was performed tomeasure the electrical conductivity, <i>i.e.</i> to determine the ionic conductivityof the film: it uses the four-point probe technique combinedwith ac impedance spectroscopy. The good agreement between measurements performedin this work (Ea = 0.75 eV, 973 K, = 3-4 10⁻³ S*cm⁻¹) and literature data allows concluding thatdeposited layers are of good quality and should be usedas electrolyte in an Intermediate Temperature Solid Oxide Fuel Cell(IT-SOFC).Read less <