Lead free (1−x)(Na 0.5 K 0.5 )NbO 3 –xBiAlO 3 (NKN–BA) piezoelectric ceramics have been prepared by a solid-state reaction method. The phase transitional behavior and various electrical properties were investigated. A pure perovskite structure can be achieved when the content of BA is less than 5%. A morphotropic phase boundary between orthorhombic and tetragonal ferroelectric phases has been identified in the composition range of 0.005≤x≤0.01. The enhanced ferroelectric and piezoelectric properties of a piezoelectric constant d 33 of 202 pC/N, a planar electromechanical coefficient k p of 46%, a remanent polarization P r of 23.6μC/cm 2 and a Curie temperature of 372°C appear in the composition with x=0.01. These results indicate that the materials studied have potential as a candidate of lead free piezoelectric ceramics.