Dielectric properties and structure of initial nanocomposite based on porous glass with embedded ferroelectric NaNO2 and nanocomposite identical to that but having a TiO2-modified pore surface, have been studied over a temperature range 300 – 450 K (on cooling) and frequency one 0.1 – 3∙106 Hz. X-ray spectroscopy of the samples exhibited that NaNO2 was in the ferroelectric phase in both composites and the percentage of crystalline NaNO2 increased in the pores of the modified one. An increase in permittivity and conductivity was observed in the TiO2-modified nanocomposite. Two relaxation processes were identified and their nature was established. The charge polarization at the interfaces was found to make the main contribution to the dielectric response of the both nanocomposites. The DC-conductivity of both composites was estimated and its activation energies were determined. An activation energy change observed in a vicinity of 400 K was attributed to the phase transition to the low-temperature phase of NaNO2. The possibility to control the properties of nanocomposites through modifying the interfaces was shown.