Based on constructal theory, the structure of a single tubular solid oxide fuel cell (TSOFC) is optimized in this paper. The maximum power output is chosen as the optimization objective. The optimal constructs of the TSOFC are obtained. The results show that the local power output P-Ej and the local current density if decrease along the flow direction. For the fixed anode, cathode and electrolyte volume fractions, there exist optimal anode, cathode and electrolyte thicknesses as well as the corresponding optimal fuel cell lengths which lead to the maximum power outputs of the TSOFC, respectively. For the fixed inner radius of the solid parts, there exist an optimal cathode thickness and an optimal fuel cell length which lead to the double maximum power output (the power output after twice maximization) of the TSOFC. The power output of the TSOFC after constructal optimization is increased by 18.20% compared to that of the TSOFC with cathode thickness t(c) = 2200 mu m and fuel cell length L = 1.5 m. The performance of the TSOFC is evidently improved by adopting the optimal constructs obtained in this paper. (C) 2015 Elsevier B.V. All rights reserved.