Piezoelectric ceramic composition comprises a compound containing Na, Li, Nb and O and having a perovskite structure as the main component which has a crystal phase in the semi-stable state at room temperature. The crystal phase is not stable at room temperature but is stable at a higher temperature. An Independent claim is also included for a process for the production of the piezoelectric ceramic composition comprising polarizing an untreated piezoelectric ceramic composition, and heating at a temperature which lies at or above the temperature at which the crystal phase is stable. The temperature is lower than a further temperature, at which the compound has no ferro-electricity. Preferred Features: The compound is of formula: (Na1-xLix)NbO3 (where x = 0.02-0.30, preferably 0.08-0.18) or of formula: (1-n)((Na1-xLix)1-yKy)(Nb1-zTaz)O3-nM1M2O3 (where x = 0.02-0.30, y = 0-0.2, z = 0-0.2, n = 0-0.1; M1 = a bivalent metallic element; and M2 = a tetravalent metallic element).