The electroluminescent properties of p-type porous silicon layers (p-PSLs) in aqueous solutions can be significantly improved by the presence of hydrogen peroxide, as demonstrated by the electroluminescence (EL) and electrochemical results presented. The possible species responsible for electron injection into the conduction band of porous silicon-necessary for EL-are discussed in the light of these results. Particular attention is paid to the possibilities of formation of HO2 during anodic treatments of p-PSLs or a reaction involving OH radicals and Si-H bonds.