Novel hydrogen-phosphonodithioate compositions are provided which are particularly useful for forming internucleotide and internucleoside linkages in oligonucleosides or oligonucleotides. The oligonucleotides and analogs thereof made by using the hydrogen-phosphonodithioate compositions may be therapeutically useful as antiviral and anticancer agents and may have other therapeutic or diagnostic uses. A method for making the hydrogen-phosphonodithioates is provided as well as a method for converting same to an activated intermediate for substitution on the phosphorus atom.