A method for the production of an aqueous dispersion of a complex of a poly(3,4-dialkoxythiophene) and a polyanion, which includes a stage in which a 3,4-dialkoxythiophene represented by the following formula (1)
- (where R1 and R2 are mutually independently hydrogen or a C1-4 alkyl group or, together, form a C1-4 alkylene group where said alkylene group is optionally substituted) is subjected to polymerization using an oxidizing agent in an aqueous medium in the presence of a polyanion, and
- in this polymerization stage said oxidizing agent is added by the dropwise addition, to the reaction liquid, of a solution or dispersion containing said oxidizing agent.