Decatungstic acid, H~4W~1~0O~3~2, can be formed and stabilized by the reaction of white powdery tungstic acid (WPTA) in aqueous solution containing polyvinyl alcohol (PVA). The H~4W~1~0O~3~2/PVA adducts have been firstly prepared as a novel conducting film of a chemical formula H~4W~1~OO~3~2.x(CH~2CHOH).yH~2O. Acid-base titration, IR and UV spectra of this film have been examined. At room temperature the films exhibit their proton conducting values from 1× 10^-^5 to 1×10^-^2S.cm^-^1 under different relative humidity and chemical composition. The photochromism of the films have also been studied.

Key words: POLYVINYL ALCOHOL, HUMIDITY, PHOTOCHROMISM