The present invention relates to novel crystalline alkali metal and alkaline earth metal salts of 2′,3′-dideoxy-2′,3′-didehydroinosine. The present invention also provides a novel process for preparation of didanosine in high yield and purity using novel intermediates. Thus, for example, 5′-O-acetyl-2′,3′-dideoxy-2′,3′-didehydroinosine is reacted with monomethyl amine to give 2′,3′-dideoxy-2′,3′-didehydro inosine, which is then reacted with sodium hydroxide and crystallized to give crystalline 2′,3′-dideoxy-2′,3′-didehydroinosine sodium salt. 2′,3′-Dideoxy-2′,3′-didehydroinosine sodium salt is hydrogenated using raney nickel catalyst in aqueous medium and then neutralized with hydrochloric acid to yield didanosine.