This work deals with textural and optical characterization of zinc oxide (ZnO) layers obtained by potentiostatic electroplating at various hydrogen peroxide concentrations (from 0 up to 5 mM). The electrodeposition process was studied by cyclic voltametry and chronoamperometry. The [002] preferred growth orientation of hexagonal phase is obtained for the lowest hydrogen peroxide concentration (1 mM), while additionally X-ray diffraction peaks are observed for hydrogen peroxide concentration ranging from 3 to 5 mM. The optical constants and the thickness of films were determined by spectroscopic ellipsometry measurements. The refractive index of all thin films shows normal dispersion behavior. It was also found that refractive index values decrease with increasing hydrogen peroxide concentration. Further, it was revealed that the changes in the optical properties are correlated to the changes in the surface structure. (C) 2009 Published by Elsevier B.V.