The oxygen surface exchange of La0.7Sr0.3MnO3 (LSM) thin films was investigated using the electrical conductivity relaxation (ECR) method. Epitaxial (100)-, (110)-, and (111)-oriented LSM films were fabricated on corresponding SrTiO3 (STO) substrates using pulsed laser deposition. The LSM films had well-controlled surface qualities, exhibited bulk-like steady-state electrical properties, and exhibited surface dominated responses in ECR. The chemical surface exchange coefficients (k(chem)) were determined and varied from approximate to 1 x 10(-6) to 65 x 10(-6) cm/s, depending on temperature and orientation, with activation energies of between 0.8 and 1.2 eV. At 800 degrees C, a four fold variation is observed in the k(chem) values, with (110)/(100) being the highest/lowest, explained well by the high activation energy for (110), approximate to 1.16 eV, and the low energy for (111) and (100), approximate to 0.83 eV. (C) 2011 Elsevier BM. All rights reserved.