Secondary phases could not be detected by XRD analysis due to the addition of 2.5 wt % of NiO.It assumed that the NiO addition in the grain boundary regions suppresses the grain growth during the sintering process, ensuing in a reduced densification of ceramic samples.With a further increase in the NiO content, εr swings in the same range.Moreover, the curie temperatures of BTO+NiO ceramics also show the same trend and the dielectric data of all samples. There are a range of ideas for explaining of the dielectric behaviors of NiO doped ceramic materials.