A rapid method for the removal of protecting groups from synthetic oligodeoxyribonucleotides, obtained by the phosphoroamidite and H-phosphonate methods, including the use of hydrazine solutions has been developed. The combination of this procedure with the application of isopropoxyacetyl N-protecting group and oxalyl ester linkage for the first nucleoside attachment to the polymer support allows to reduce to several minutes the time needed for the full oligonucleotide deprotection.