Poly(o-aminophenol) has been synthesized potentiostatically at different electrode potentials in aqueous acidic solution. The cyclic voltammograms of the POAP films synthesized at relatively low electrode potentials (E-SCE = 0.70...0.80 V) exhibit two redox processes with a mid point potential between the respective redox potentials E-SCE = 0.29 V showing that the redox transition of the POAP from its reduced to completely oxidized state occurs via two consecutive reactions. The polymer has been studied with in situ UV-Vis and in situ Raman spectroelectrochemistry. The nature of a Raman band observed around 1645 cm(-1) with red Kr+ laser excitation (647.1 nm) is discussed. The intensity of this band grows during a positive potential shift up to a maximum, located at about E-SCE = 0.30 V, and then decreases with a further potential shift indicating the existence of intermediate species during the redox transformation of the polymer. (c) 2006 Elsevier B.V. All rights reserved.