The crystalline structure and phase composition of epitaxial thin Ag2S films grown by thermal co-evaporation of Ag and S on mica substrate were studied by electron-optical methods. It was established that a careful post-deposition annealing improves substantially both the degree of crystallinity and phase composition of as-grown films. Electron diffraction patterns and DC dark ionic conductivity measurements present an experimental evidence for preparation of single-crystalline samples when appropriate conditions of deposition and thermal annealing were chosen. (C) 2004 Elsevier B.V. All rights reserved.