Polyaniline was electrodeposited on an insulating-host matrix, Bentonite (clay mineral). Cyclic voltammetry was used to characterize the electrochemical response. Results show that aniline was trapped in the Bentonite/Polyaniline composite matrix and that the rate of polyaniline electrodeposition from this trapped aniline is different from that of the bulk solution. The electrochemical degradation rates are also different. (C) 2000 Elsevier Science B.V. All rights reserved.