PVA films containing 12-tungstogermanic heteropoly acid have been successfully prepared for the first time. Infrared (IR) spectra revealed that the Keggin structure characteristic of the GeW12O440y anion was present in the PVA films. The characteristic IR peaks have been identified and their change in wave number interpreted as a function of heteropoly acid (HPA) content. The film exhibited considerably high proton conductivity, which increased with the increase of the 12-tungstogermanic heteropoly acid content. At room temperature (208C）, the conductivity of the PVA film containing 80 wt.% 12-tungstogermanic heteropoly acid is 2.11=10y2 S cmy1. The photochromism of the PVA film was observed. Its color changed into blue. q2001 Elsevier Science B.V. All rights reserved.