The reduced viscosity, eta(R), of poly(vinyl alcohol)-Congo red (PVA-CR) complexes in aqueous solution has some unique features, such as (1) an appearance of a maximum at a given PVA concentration (C-PVA) and (2) a time evolution of eta(R), but only in the regime where the maximum appears. These characteristic features of the viscosity behaviour are simulated by using the theory of Rice and Kirkwood which takes into account the electrostatic interaction in the reduced viscosity.