Selective reduction of nitroarenes to give the corresponding anilines was carried out conveniently with sodium dithionite (Na2S2O4) by using insoluble resins with a viologen structure as electron-transfer catalyst (ETC) under heterophase condition. An EPR method confirmed that a viologen radical, the one-electron reduction product (V·+), acted as the catalytic active species during the reduction of nitroarenes. A reaction scheme involving an aniline radical has been proposed. © 1997 Elsevier Science Ltd. All rights reserved