A novel chemically-modified electrode containing 12-molybdophosphoric acid was achieved on the surface of platinum electrode by sol-gel technique. The electrochemical behavior of the modified electrode was characterized by cyclic voltammetry in detail. The film electrode obtained was very stable and exhibited electrocatalytic response for reduction of bromate, chlorate and hydrogen peroxide. Hydrogen peroxide was determined amperometrically at the modified electrode in the concentration range of 3 x 10(-2) to 2 x 10(-5) M and a detection limit of 7 x 10(-6) M (signal-to-noise ratio 3). (C) 2000 Elsevier Science Ltd. All rights reserved.