Aurivillius type Na-0.46-Li0.04Bi0.5-x(LaNd)(x/2)Bi2Nb2O9 ceramics were prepared by a conventional solid state sintering method. The evolution of crystal structure, microstructure and corresponding electrical properties were studied. A new pseudo morphotropic phase boundary between orthorhombic to pseudo-tetragonal phases was identified near x similar to 0.06, giving rise to the enhancement of piezoelectric properties. The resonance and anti resonance impedance modulus at rising temperatures demonstrated that the ceramics with 6 mol% La3+/Nd3+ doping (NLN-6) was indeed piezoelectric in nature at 700 degrees C. The electrochemical impedance spectra indicated that thermally excited intrinsic oxygen vacancies were responsible for both electrical conduction and dielectric relaxation processes. The NLN-6 ceramics exhibited superior electrical properties (d(33) similar to 20.1 pC/N, k(p) similar to 6%, T-c similar to 737 degrees C, rho similar to 1 M Omega.cm@600 degrees C) and also possessed excellent stability of piezoelectric properties with rising temperature. These results suggest that La3+/Nd3+ multi- rare-earth ions modified Na0.46Li0.04Bi2.5Nb2O9 ceramics are promising candidates for ultra-high temperature piezoelectric applications.