Thin porous silicon (PS) based metal/PS/p-c-Si structures were prepared on moderate-and high- resistivity substrates. Measurements of current-voltage (I-V) dependencies and impedance at various temperatures were used for the investigation of carrier transport in these structures. The exponential forward bias I-Vdependencies for both types of structures spread over several orders of magnitude with a low value of quality factor (close to 2) and have activation temperature dependencies with an activation energy equal to half the c-Si band gap. The reverse current has a square root dependence on the reverse bias voltage and the activation energy is equal to half the c-Si band gap. Therefore, it was concluded that the reverse and forward currents in thin PS-based device structures were determined by the generation and recombination of carriers in the depletion region of the c-Si substrate. It was shown that a large area spreading current exists in structures made on highly resistive substrates, which appears to be due to a highly conductive inverse (n-type) layer formed in the c-Si substrate at the PS/c-Si heterojunction.