In this work an attempt is made to study [Pb(Zr0.53Ti0.47O3)O-3](1-X)-[Pb(Y0.5Nb0.5)O-3](X) system with x = 0.0125, 0.025, 0.05, 0.075 and 0.1. It was shown that there is limited solid solubility (2.5 mol%) of Pb(Y0.5Nb0.5)O-3 (PYN) in PZT (53/47). The substitution of PYN gave rise to the reduction of the volume of PZT's unit cell. For the samples doped above this level of PYN, an extra phase comprising of Y3+, Zr4+ and Ti4+ cations were detected based on EDS-SEM and XRD analysis and also a structural shift towards a rhombohedral phase was noticed for the main PZT phase. Further, the addition of PYN up to 2.5 mol% was seen to increase the room temperature relative permittivity and d(33) parameter. However, these parameters declined for the samples substituted with more than 2.5 mol% PYN due to the formation of non ferroelectric extra phase.