A glassy carbon microelectrode has been modified with multilayer films of 2-anthraquinonyl groups (AQ(L)), and characterised in three different room temperature ionic liquids (RTILs). The electroactivity of the anthraquinonyl films was found to vary with the size of the RTIL cation, in that the extent of the AQ(L)(center dot-)L/AQ(L)(2-) reduction was found to decrease with increasing cation size. Two distinct one-electron redox waves were observed in RTILs composed of smaller cations, while only a single one-electron wave was observed in RTILs composed of larger cations. It is proposed that complete reduction of the film cannot be achieved using larger RTIL cations, as steric hindrance within the film inhibits charge compensation. (C) 2011 Elsevier B.V. All rights reserved.