In this work, the structure, electrical, and dielectric properties of nano size structured of MnO2 were studied. The preparation was carried out through hydrothermal processes of a mixture of KMnO4 solution, HNO3, and SiO2 at 180°C in various dwell times of reaction: 7, 9, and 20 hours. X-ray powder diffraction (XRD) patterns of all prepared samples were identified δ-MnO2 having nano-size particle. Micro-strain and dislocation inside the grains were also presented. The impedance complex analysis Z′ - Z″ plots were performed in the frequency range of 0.1 Hz-32 MHz and room temperature signing grains and grain boundaries resistance and capacitance electrical circuit network. The AC conductivity, and dielectric properties: relative permittivity, areal capacitance, losses (tan δ), were explored to analyzed structural variation related to sample preparation.