LSM (La0.85Sr0.15MnO3-delta)-SDC (Sm0.2Ce0.8O1.9) composites, which are based on LSM matrices embedded with SDC particles, were fabricated with an ion-impregnation technique as cathodes for intermediate and low temperature solid oxide fuel cells(SOFCs). Effect of heat-treatment temperatures for both LSM matrices and SDC particles was investigated on cathodic interfacial polarization resistances. When the matrix was fired in the range of 800-1000 degrees C, low temperature resulted in high specific surface area, and therefore low resistance. On the contrary, high temperature enhanced the bonding between the particles and matrices, and consequently caused increased electrochemical performance when the impregnated SDC was heated at temperature from 700 degrees C to 800 degrees C. With the impregnated LSM-SDC composite as the cathode, a single cell generated 138 mW/cm(2) at 600 degrees C when humidified H-2 was used as the fuel, suggesting that it is possible to use LSM as the cathodes for SOFCs that operated at low temperature when the microstructure is further optimized. (C) 2007 Elsevier B.V. All rights reserved.