Polypyrrole (PPy) and poly(3,4-ethylenedioxythiophene) (PEDOT) conducting polymers are being applied in a number of devices due to their intercalation redox activity and conductivity. Their use as electrode materials in bio-applications has been hindered by the large irreproducibility of surfaces for the most common counterions, specially in the PEDOT case. This work shows that the best behavior in neural cell cultures does not belong to one or the other polymer, but to a combination of both, and specific counterions. Polypyrrole, with surface potentials closer to biological systems, becomes an optimal surface, but only when electrodeposited on PEDOT and with some biologically active aminoacids acting as counterions. Characterizations of the surface PPy and its electrochemical response are performed. The formation of bilayers, with PPy deposited on PEDOT, significantly changes the conductivity and charge capacity of PPy polymer, largely improving the neural cell growth on these polymers in a reproducible manner. (C) 2013 Elsevier Ltd. All rights reserved.