Films obtained after cathodic polarization at E-c, -0.2 V less than or equal to E-c less than or equal to 0.1 V (vs. RHE), in aqueous acid perrhenate have been investigated using cyclic voltammetry and ellipsometry. The thickness and optical indices corresponding to the electrodeposited rhenium layer were calculated. The results indicate the formation of a composite layer, with a volumetric fraction of about 30% of metallic rhenium and hydrogen occlusion.