Group-IV semiconductor nanowires (NWs) are attracting the interest of a wide scientific community as building blocks for a wide range of future nanoscaled devices. We used metal-assisted chemical etching of Si substrates to synthesize Si NWs with different length and nanometer-size diameter. NWs obtained by this technique have exactly the same structure and doping of the substrate and present quantum confinement effects. Photoluminescence (PL) emission at room temperature from Si NWs is reported. We observed an increasing behaviour of the PL intensity as a function of the NWs length. The fabrication of light emitting devices based on Si NWs, showing electroluminescence emission at room temperature under low voltage excitation, is also reported.