The initially hydrophobic surface of as-prepared luminescent stain-etched porous Si powder is made hydrophilic by means of the physical adsorption of different nonionic surfactants. Unsaturated linear hydrocarbons (undecylenic acid and oleyl alcohol) are found to provide the best durability of aqueous suspensions of porous Si powder, maintaining the ability of excited Si nanocrystals to interact with molecular oxygen by means of electronic energy transfer.