WO3 is a promising active material for electrochromic application. In this study, 5% Al2O3 doped WO3 layers were investigated. The thickness of the deposited material was measured as 132 nm and the refractive index at 550 nm wavelength was measured as 1.92. The band gap energy of the doped material was calculated by the Tauc-Plot method and it was found as 3.95 eV. Electrochromic (EC) measurements of the material were obtained in the voltage range of −0.6 V to +0.6 V. The intercalated/de-intercalated charge amounts into the material were calculated as 0.40 mC and 0.14 mC, respectively. It was observed that colored time was 14 s and bleaching time was determined as 20 s. The material was performed to a 300-cycle test. That is, 5% Al2O3 doped WO3 layers is promising material for the EC application.