The results of studying the dielectric constant σ' and the third harmonic coefficient γ3ω of a new organic ferroelectric diisopropylammonium bromide (C6H16NBr, DIPAB), embedded in porous glasses with an average pore size of 100 nm are presented. Diffusion and shifting of the phase transition to low temperatures by 5 K were detected in comparison with bulk DIPAB. A decrease in the phase transition temperature in nanocomposites with DIPAB nanoparticles is qualitatively consistent with theoretical models of the size effects on the structural phase transition.