A thermally stable and self-sustainable portable energy conversion system is designed using low temperature thin film SOFCs (solid oxide fuel cells). Hydrogen and air gases are fed into this system, which is successfully operated at 319 degrees C. Each cell, comprised of Pt (anode)/YSZ-GDC-YSZ/Pt (cathode), is manufactured using sputtering and atomic layer deposition, and the area of a single cell is 2.56 cm(2). The maximum absolute power and power densities at 500 degrees C are measured to be 44 mW and 17 mW cm(-2), respectively. To the best of our knowledge, this represents the highest absolute power reported at such a low operating temperature regime. To increase the system's temperature, a catalytic burner using Al2O3 and a Pt catalyst is manufactured by dip-coating. After hydrogen gas and air pass through the anode and cathode sides, respectively, the mixed fuel gases are supplied to the catalytic burner, which undergoes an exothermic reaction. We successfully demonstrate that this system is heated up to 319 degrees C (from room temperature) without any other initial heat source; we also measure the electrical power simultaneously. (C) 2016 Elsevier Ltd. All rights reserved.