Electrical properties of binary samples containing photoconducting poly [methyl(phenyl)silylene] with admixed photo-chromic spiropyran were investigated. A reversible chemical reaction of the photochromic system, driven by light and producing highly polar metastable species, manifests itself in a reversible modification of dark currents and photocurrents. The behaviour of the samples is explained assuming a reversible production and annihilation of dipolar traps associated with the polar molecules produced in the photochromic process. Use of similar materials as elements of molecular electroactive systems is postulated. (C) 2004 Published by Elsevier B.V.