La0.8 Sr0.2 Co0.8 Fe0.2 O3 (LSCF) nanopowders, which are being investigated as a promising cathode material for low-temperature solid oxide fuel cells (SOFCs), were synthesized by citric acid gel combustion method. The LSCF nanopowders synthesized at 700°C are single perovskite phases and have an average particle size of less than 30 nm. In order to evaluate the use of the synthesized LSCF nanopowders as cathode material of low-temperature SOFCs, anode-supported SOFCs were fabricated from the synthesized LSCF nanopowders and tested in the conditions of humidified hydrogen for anode and oxygen for cathode. The anode-supported single cell with the LSCF cathode sintered at 700°C showed high electrical performance with the maximum power density of 771 mW cm−2 at 600°C. The results show that the synthesized LSCF nanopowders are suitable to be applied as cathode material for low-temperature SOFCs.