The potential utilization of two-stage sintering for the production of highly dense and pure nickel diniobate (Ni 4 Nb 2 O 9 ) ceramics with low firing temperature was demonstrated. Effects of designed sintering conditions on phase formation, densification and microstructure of the ceramics were characterized by X-ray diffraction (XRD), Archimedes method and scanning electron microscopy (SEM), respectively. It has been found that minor phase of columbite NiNb 2 O 6 tended to form together with the desired Ni 4 Nb 2 O 9 phase, depending on sintering conditions. The optimization of sintering conditions could lead to a single-phase Ni 4 Nb 2 O 9 ceramics with orthorhombic structure. The ceramics doubly sintered at 950/1250 °C for 4 h exhibited maximum density value of  92%. Microstructures with denser angular grain-packing were generally found in both sets of the sintered Ni 4 Nb 2 O 9 ceramics. However, the grains were irregular in shape when the samples are sintered at 1050/1250 °C. Two-stage sintering was also found to enhance ferroelectric behavior of Ni 4 Nb 2 O 9 ceramic. PAC S no. 77-84 Bw