(Sr 0:5 Ba 0:5 )Nb 2 O 6 ultra-fine powders were synthesized by a novel sol-gel route, and the mechanism of the reaction was discussed. SrCO 3 , BaCO 3 , oxalate niobium and citric acid were used to initiate the sol-gel process, and ethylene glycol (EG) was added to further polymerize the cross-linking structure. The evolution of the (Sr 0:5 Ba 0:5 )Nb 2 O 6 phase, the reaction process and the microstructures were investigated by X-ray diffraction (XRD), Raman spectroscopy, Fourier transform infrared spectroscopy, DSC-TG and scanning electron microscopy. The synthesis temperature of the (Sr 0:5 Ba 0:5 )Nb 2 O 6 powders reached as low as 1200 C, and the size and morphology of the powders were controlled by temperature. By adjusting the calcination temperature, we obtained (Sr 0:5 Ba 0:5 )Nb 2 O 6 powders with uniform sizes of 20 nm to 500 nm. Then, dense (Sr 0:5 Ba 0:5 )Nb 2 O 6 ceramics were successfully prepared using these ultrafine powders. Finally, an enhanced electrocaloric effect (ECE) value of 0.35 C was obtained at 100 kV/cm.