We studied the impact of electrical isolation (passivation) of metallic particles on induced polarization (IP) parameters. We carried out laboratory experiments with six synthetic models made of sieved sand mixed with metallic particles. The purpose of this experiment was to understand what mechanism (polarization of positive and negative charge carriers within the particles or interfacial polarization) was responsible for the IP effect. Size and location of passivated zones on the particle surfaces varied from model to model. We observed a decrease of the total chargeability and relaxation time values with the increase of passivated surface. Fully passivated metallic particles showed no IP effect. These data suggest the dominant role of the interface phenomena in IP associated with metallic particles.