A low-frequency impedance analyzer was used to measure the conductivity of crude-oil-derived asphaltene and deposits. The conductivity varies from a slow increasing function to a drastically increasing one upon increasing the frequency of the applied electric field. A consistent difference, in regard to the response between the deposit and the crude-oil-derived asphaltene from the same source, was observed. A transition of charge-transfer mechanisms was revealed at a frequency of similar to0.56 MHz.