Noble metals Pt and Pd decorated on cathode materials can effectively improve the performance of solid oxide fuel cells. Here, we explore the promotion effect of metal nanoparticles on the surface exchange reaction rates of (La,Sr)MnO3 (LSM) as a function of temperature and the LSM orientation. The surface chemical exchange coefficient, K-chem, is investigated using electrical conductivity relaxation (ECR) method for Pt and Pd decorated epitaxial (001)-, (110)-, and (111)-oriented LSM films. Compared with the bare LSM film, larger K-chem is observed with the Pd and Pt nanoparticles decorated LSM films at the temperature in the range from 500 degrees C to 650 degrees C. Pt nanoparticles decorated on (110)-LSM promotes the surface exchange rate to a factor up to 129, about 5 times higher than the Pd decorated (110)-LSM. (C) 2017 The Electrochemical Society. All rights reserved.