A simple method for the morphology modification of electrodeposited WO3 films is presented. it is based on the tendency of the peroxotungstic acid precursor to conglomerate within its solution towards grape-like structures. It has been shown that WO3 films deposited 48 h past the precursor formation incorporate the aforementioned formations in their structure and have a higher effective surface area and improved ion mobility compared to similar films prepared immediately after the synthesis of the precursor. We have used the above method to fabricate electrodeposited WO3 films with modified morphology, 1300 nm thick, with Li ion diffusion coefficient values as high as 4.5 x 10(-10) cm(2)/s. These films exhibit promising electrochromic coloration properties. (C) 2008 Elsevier B.V. All rights reserved.