The invention relates to a process for dissolving at least one compound of low solubility in water, the said process comprising the essential step of mixing the compound of low solubility with at least one lipophilic amino acid derivative. The invention also relates to a cosmetic or dermatological composition comprising, in a physiologically acceptable medium, at least one compound of low solubility and at least one lipophilic amino acid derivative. Among the compounds of low solubility that are especially included are aminophenol derivatives, salicylic acid derivatives, 2-amino-4-alkylaminopyrimidine 3-oxide derivatives and DHEA, and also its chemical or metabolic derivatives and precursors.