The mixed ionic and electronic conductors (MIEC) of La0.9Sr0.1Co0.8Ni0.2O3-delta (LSCN)-Ce0.8Sm0.2O1.9 (SDC) were investigated for potential application as a cathode material for solid oxide fuel cells (SOFCs) based on a SDC electrolyte. Electrochemical impedance spectroscopy (EIS) technique was performed over the temperature range of 600-850 degrees C to determine the cathode polarization resistance, which is represented by area specific resistance (ASR). This study systematically investigated the exchange current densities (i(o)) for oxygen reduction reaction (ORR), determined from the EIS data and high-field cyclic voltammetry. The 7OLSCN-30SDC composite cathode revealed a high exchange current density (i(0)) value of 297.6 mA/cm(2) at 800 degrees C determined by high-field technique. This suggested that the triple phase boundary (TPB) may spread over more surface of this composite cathode and revealing a high catalytically active surface area. The activation energies (E-a) of ORR determined from the slope of Arrhenius plots for EIS and high-field techniques are 96.9 kJ mol(-1) and 90.4 kJ mol(-1), respectively. Copyright (C) 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.