By variation of hydrothermal synthesis key factors such as pH, temperature and capping agent, plate and rod-like boehmite nanoparticles were obtained. The nanoparticle structure was confirmed by X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Transmission Electron Microscopy (TEM), and Dynamic Light Scattering (DLS). Aqueous suspension of boehmite particles was studied using electro-optical technique. The suspensions were confirmed to be sufficiently stable, which allowed to determine the structure of boehmite particle electric double layer (EDL). The Dukhin-Shilov theory of EDL conductivity described the observed electro-optical effects well. The values of boehmite particle surface conductivity were obtained at different KCl electrolyte concentrations.