Ferroelectric ceramics were discovered in the 1940s in polycrystalline barium titanate (von Hippel et al., 1946; Wul & Goldman, 1945), since then, there has been a continuous succession of new materials and technology developments that have led to a significant number of industrial and commercial applications. Structurally speaking there are four types of ferroelectric ceramics: (1) perovskites, (2) the tungsten-bronze group, (3) pyrochlores and (4) the bismuth layer-structure group. Of these, the perovskites (ABO3) are by far the most important category. The families with composition BaTiO3, PbZr1-xTixO3 (PZT), PZT:La (PLZT), PbTiO3 (PT), Pb(Mg1/3Nb2/3)O3 (PMN) and (K0.5Na0.5)NbO3 (KNN) represents most of the ferroelectric ceramics manufactured in the world (Haertling, 1999). In this chapter the structure of calcium titanium oxide (CaTiO3), the ferroelectrics ceramics BaTiO3, Na0.5Bi0.5TiO3 (NBT), K0.5Bi0.5TiO3 (KBT) are described as well the concept of hysteresis loop, ferroelectric domains and why lead free materials are now in the top of the interest in ferroelectric and piezoelectric materials. The aim of this chapter is to present results of the synthesis, characterization and piezoelectric properties of two lead free piezoelectric compounds: K0.5Na0.5NbO3 and (K0.48Na0.52)0.96Li0.04Nb0.85Ta0.15O3.