A new method for obtaining functional polymer films is described, consisting in a combination of the evaporation technique and the electropolymerization method. The electropolymerization of the vacuum-evaporated 1-pyrenamine monomer film was studied and it was found that polymerized 1-pyrenamine showed an electrochromic colour change from brown to yellow upon reduction. Moreover, the pH dependence of the polymerization was found to be caused by a difference in the stability of a transient species in electrolyte solutions of different pH. A mechanism for this pH dependence is discussed from the standpoint of the wettability of the evaporated monomer film by the electrolyte solutions.