A conducting polymer, emeraldine form of polyaniline (PANI), reduces silver nitrate to metallic silver. The composites of PANI and silver have been prepared at equimolar proportion of reactants. Seven acids, representing inorganic and organic acids, have been used to protonate PANI. The acids were selected with respect to their chemical indifference or the ability to precipitate or reduce silver(I) ions. The PANI-silver composites differed in the conductivity from 1.7 x 10(-6) S cm(-1) when PANI phosphate was used as a substrate to 22.8 S cm(-1) for PANI hydrochloride at comparable silver contents, 24 and 27 wt.% The protonation state of PANI in PANI-silver composites was analyzed by FTIR spectroscopy. The composites contained spherical silver nanoparticles of 40-80 nm in size and also macroscopic particles, irrespective of PANI entering the reaction. (C) 2008 Elsevier Ltd. All rights reserved.