A single-phase Cu-Al alloy with a low stacking fault energy was processed by cold rolling and subsequent annealing. Fully recrystallized microstructures composed of ultrafine grains were obtained after isothermal annealing at different temperatures. The minimum mean grain sizes achieved were below 1 mu m. It was found that the microstructures were homogeneous after annealing at 400 A degrees C, but somehow inhomogeneous after annealing at lower temperature of 300 A degrees C and higher temperature of 550 A degrees C. Superior strength and ductility were obtained by controlling the grain size of the microstructures. After annealing at 400 A degrees C for 10 s, a fully and homogeneously recrystallized material with mean grain size of 770 nm was produced, which had a high yield strength of 524.2 MPa and a remarkable uniform elongation of 15.7 %.