This study investigates the electrical properties of (K0.5Na0.5)NbO3 (KNN) lead-free piezoelectric ceramics prepared by using monoclinic Nb2O5 as the starting material. The results reveal that the samples prepared by two-step sintering procedure are much better than those prepared by conventional sintering procedure. The piezoelectric constant (d33) reaches the value measured from the samples prepared from orthorhombic Nb2O5, suggesting the two-step sintering procedure could be an effective method to remove the negative effect of monoclinic Nb2O5. The underlying mechanism for the improving effect is discussed
