The synthesis and stability studies in several aqueous media of mononucleoside glucosyl phosphotriester derivatives of 3'-azido-3'-deoxythymidine are reported herein. Such neutral mononucleotides, which incorporate beta-glucopyranosidyl moieties associated to a thioethyl linker as phosphate protecting groups were designed to act as "pronucleotides", giving rise to the corresponding 5'-mononucleotide through a glucosidase-mediated activation mechanism.