Electrolyte effects on the oxygen surface exchange coefficients of strontium-doped lanthanum manganates (LSM) are investigated using electrical conductivity relaxation technique. Introducing electrolytes can significantly reduce the re-equilibration time, demonstrating the substantial promotion in the surface exchange kinetics. The coefficient at 1000 degrees C increases from 9.00 x 10(-5) cm s(-1) for pure LSM to 2.45 x 10(-4) cm s(-1) for LSM coated with yttria-stabilized zirconia, and further increases to 7.92 x 10(-4) cm s(-1) for LSM with samaria-doped ceria. The nearly one order of magnitude increase in the coefficient demonstrates that introducing electrolytes can effectively increase the electrochemical performance of solid-oxide-fuel-cell cathodes by enhancing the surface exchange reaction in addition to extending the reaction sites. Copyright (C) 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.