Data have been presented on the electrical polarizability and surface conductivity of goethite particles in aqueous polydisperse systems. The polarizability of the particles has been experimentally studied by the electrooptical method. Functions of particle distribution over polarizability anisotropy values and sizes have been found. For suspensions containing an electrolyte (KCl), dependences of polarizability anisotropy of the particles on electric field frequency have been experimentally determined in a frequency range of 500Hz to 2.5 MHz. In addition, dependences of polarizability anisotropy and surface conductivity of the particles on KCl concentration in suspensions have been found. These dependences have shown that the particle polarizability decreases and the surface conductivity increases with a rise in KCl concentration. The surface conductivity of the particles varies in proportion to KCl concentration.