Porous silicon (PS) on n-type and p-type crystalline silicon (c-Si) devices were obtained by electrochemical HF etching of Si wafers. In order to obtain electronic devices based on porous silicon on crystalline silicon structure, the first step is to obtain good electrical contacts on the porous layer. For this reason, several metal/PS/metal and metal/PS/c-Si/metal junctions were electrically characterized. An electrical model was proposed in order to explain the measured current-voltage characteristics. Finally, first results of PS/c-Si devices such as NH3 and humidity sensors were presented.