Porous silicon has potential applications not only in optoelectronics but also in the areas of sensors and biomaterials. Research in this direction relies on the sorptive properties of the material, which means that fundamental adsorption studies are important. The various pore morphologies of porous silicon are reviewed, as are the types of experiments that have been performed related to adsorption from the gas and liquid phases, along with their results. It is suggested that three-dimensional surface-physics-oriented studies would lead to interesting insights.