Oxidation of vitamin D₂(Ⅰ) with neutral or weak alkaline permanganate gives rise to a new dihydroxy-dihydrovitamin D₂(C₂₈H₄₆O₃),the struture of which has been proved to be 7,8-dihydroxy-7,8-dihydrovitamin D₂(XIa) on the basis of spectral analysis,acetate formation and oxidative degradation.The new dihydroxy compound [slender platelets,m.p.177-178°,[a_D¹⁸+97.4° (c],methanol)]shows an absorption maximum at 221 mμ (3.83)(Fig.1),which gives a diacetyl derivative(7,8-dihydroxy-7,8-dihydrovitamin D₂-3,7-diacetate (XIb) on acetylation with acetic anhydride and pyridine [C₃₂H₅₀O₅,m.p.100.5-101.5°,[a]_D¹⁸+72° (c 1,methanol),λ_max, 220 mμ,(3.74)].