Solid oxide fuel cells with nano-sized Co1.5Mn1.5O4 (CMO) crystals infiltrated LSM-YSZ cathodes have been investigated using XRD, SEM, EIS and cell performance measurements. 20 similar to 30 nm nanocrystals of Co1.5Mn1.5O4 are present on the surfaces of LSM and YSZ particles. The infiltrated cells display more than 2 times higher power density than the non-infiltrated cell under 0.7 V at the same temperature in 600-700 degrees C. The Co1.5Mn1.5O4 infiltration reduces both ohmic resistance and polarization resistance in the cells. The distribution of relaxation times (DRT) analysis of the EIS data depicts that oxygen reduction process is greatly accelerated on the infiltrated cathode, which is attributed to high catalytic activity of nano-sized CMO crystals. Copyright (C) 2015, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.