We report for the first time the development of a new surface-enhanced Raman scattering (SERS)-active silver chloride silica-glass substrate prepared by using in situ precipitation of silver chloride particles in sol-gel films as a precursor for nanoparticles of silver. The controlled precipitation of silver chloride was achieved by the reaction of silver nitrate with trichloroacetic acid, which leads to a slow release of chloride ions. Silver chloride particles were reduced to silver nanoparticles by FeSO4. 7H(2)O. The sol-gel films prepared exhibit good optical properties and induce a strong SERS effect for several model compounds, including cresyl fast violet and brilliant cresyl blue. Optimization studies of substrate preparation and coating conditions were performed and are discussed in detail. The performance of this new substrate compares favorably with those of previously developed silver-coated alumina substrates, The SERS spectra of other compounds of environmental and biological interest, such as 1-aminonaphthalene, 2-aminopyrimidine, pyridine and p-aminobenzoic acid, were investigated to illustrate the usefulness of this novel type of SERS substrate for use in chemical and biological analysis. Copyright (C) 1999 John Whey & Sons, Ltd.