In this work we have explored the electrochemical properties of two lithiated iron oxide powders for supercapacitor purposes. These samples mainly consisted of alpha-LiFeO2 in nanosized or micrometric form. Electrolyte was an aqueous 0.5 M Li2SO4 solution and voltage range studied was between 0 and -0.7 V vs. a Ag/AgCl reference electrode. As expected, electrochemical performance was dependent on the particle size. When electrolyte was deaerated a stable capacitance of approximate to 50 F g(-1) is provided by the nanosized sample for several hundred cycles. Other sulfate based salts (Na2SO4, K2SO4, Cs2SO4) were investigated as electrolytes but only Li2SO4 leads to a stable capacitance upon cycling, probably due to lithium intercalation. An hybrid cell consisting of this sample and MnO2 as negative and positive electrodes, respectively, delivered 0.3 F cm(-2) (10 Fg(-1)). Although these values are lower than reported for other aqueous hybrid cell, alpha-LiFeO2/MnO2 asymmetric capacitor is interesting from both, an economic and an environmental point of view. (C) 2010 Elsevier Ltd. All rights reserved.