A simple but effective passivation method for porous silicon (PS) has been developed. Immersion of as-etched PS in dilute (NH4)(2)S/C2H5OH solution followed by ultraviolet light irradiation in air can lead to an enhancement of photoluminescence (PL) up to more than 20 times. Infrared absorption and Auger electron spectroscopic measurements show that the formation of SiH(O-3), Si-O-Si and Si-N bonds are formed during the post-treatment process. However, the PL intensity cannot be enhanced if the solution-treated sample is exposed to the laser beam in vacuum. It is thus concluded, that the PL enhancement can be attributed to the presence of compact passivation films consisting of the oxides and the nitride on both external and internal surfaces of the sponge-like PS samples.