The electrochromic properties of the mixed-ligand zirconium phthalocyanine complex films have been investigated. Voltammetric characteristics, absorption spectra of films as a function of potential, and curves of current and absorption at the Q-band maximum in the case of their reversible oxidation in 1 N KCl against time have been measured. An analysis of the time-current dependence allowed us to find that the dynamics of the reversible oxidation of phthalocyanine complexes in such films are determined by the codiffusion in their bulk of positive and negative carriers (as Cl- anions) with effective diffusion coefficient D-eff = similar to 10(-13) cm(2)/s. The same value of D-eff has been obtained from measurements of the curve of optical density in the region of the Q-band maximum against time. (C) 2009 Elsevier B.V. All rights reserved.