Metal contacts have been deposited on porous silicon obtained from n epitaxial layers and from n(+) substrates. The optical properties of the material have been verified. The current-voltage (I-V) characteristics of the metal/porous silicon/crystalline silicon structures are poorly reproducible from sample to sample, even in the case of the same fabrication process, A common trend was observed in the semilog I-V plane, that is a change of the slope d(lnI)/dV which occurred for forward voltages of about 0.5 V. Instabilities and current degradation effects have been observed in the forward current at room temperature. I-V measurements on annealed Schottky contacts and free-standing layers indicate that the metal-porous silicon barrier plays a significant role in the transport mechanisms.