La0.7Sr0.3MnO3 thin films were deposited on SiO2/Si substrates by RF magnetron sputtering under different oxygen gas flow rates with a sputtering power of 100 W. During deposition, the substrate was heated at 623 K. To investigate post-annealing effects, the as-deposited La0.7Sr0.3MnO3 thin films were thermal-treated at 973 K for 1 h. The effects of oxygen gas flow rate and post-annealing treatment on the physical properties of the films were systematically studied. X-ray diffraction results show that the growth orientation and crystallinity of the films were greatly affected by the oxygen gas flow rate and substrate heating during deposition. The sheet resistance of the films gradually decreased with increasing oxygen gas flow rate, while the post-annealed films showed the opposite behavior. The temperature coefficient of resistance at 300 K of La0.7Sr0.3MnO3 thin films deposited at an oxygen gas flow rate of 40 sccm decreased from - 2.40%/K to - 1.73%/K after post annealing. The crystalline state of the La0.7Sr0.3MnO3 thin films also affected its electrical properties. (C) 2010 Elsevier B.V. All rights reserved.