Choline can be covalently grafted on glassy carbon electrodes using cyclic voltammetric method, forming a stable cationic monolayer-modified electrode (Ch/GCE). Keggin-type molybdophosphate anions, alpha-PMo(12)O(40)(3-), then were self-assembled on the Ch/GCE through electrostatic interactions for fabrication of an electrochemical sensor, which is denoted as alpha-PMo(12)/Ch/GCE. This two-layer modified electrode was carefully characterized by cyclic voltammetry and X-ray photoelectron spectroscopy. It was found that the sensor exhibits strong electrocatalytic activity and sensitivity toward the reduction of IO(3)(-). The content of IO(3)(-) in a table salt was determined with satisfactory results. The sensor is promising as an electrochemical sensor for the detection of IO(3)(-).