The results of a study of linear and nonlinear dielectric properties, as well as calorimetric measurements of a ferroelectric composite (C6H16NBr)1–x/(PbTiO3)x with a volume fraction x = 0.1, 0.2, 0.3 of lead titanate particles are presented. It has been shown that the addition of lead titanate particles to diisopropylammonium bromide leads to a change in the sequence of structural phase transitions in the diisopropylammonium bromide, an increase in the effective dielectric constant and tanδ values. In a temperature range of 150 – 138 ° C, there were two C6H16NBr phases (ferroelectric P21 and nonferroelectric P212121). The proportion among these phases depended on the fraction of lead titanate particles in the composite.