The solid solution between the antiferroelectric, PbZrO3 (PZ), and relaxor ferroelectric, Pb(Ni1/3Nb2/3)O3 (PNN), was synthesized by the columbite method. The phase structure and phase transition of Pb(Zr1-x(Ni1/3Nb2/3)xO3 (PZNN), where x = 0.0 ≤ x ≤ 0.50, were investigated. The samples were kept at the calcination temperature of 900°C for 4 h and at the sintering temperature of 1,150°C for 2 h. Phase formation and phase transition of PZNN were investigated by x-ray diffraction (XRD) and thermal analysis, respectively. It was found that the structure of sintered pellets is orthorhombic for 0.0 ≤ x ≤ 0.10, rhombohedral for 0.20 ≤ x ≤ 0.30 and pseudo-cubic for x = 0.5. DSC measurement shows that in the antiferroelectric (AFE) phase – ferroelectric (FE) phase and FE to paraelectric (PE) phase; phase transformation temperatures decrease with increasing PNN concentration. The AFE–FE phase transformation was detected for compositions 0.00 £ x £ 0.08.