The invention relates to a process for obtaining Estetrol or a salt or solvate thereof, the process comprising: a) reacting a compound of formula (IV) or a salt or solvate thereof, wherein R1 is a hydroxyl protecting group selected from a silyl ether, an ether, an ester, a carbamate and a carbonate, and R2 is a hydroxyl protecting group selected from an ether, with an oxidizing agent selected from OsO4 or a source of osmium tetroxide to produce Estetrol or a compound of formula (II) or a salt or solvate thereof wherein R1 is as defined previously; and b) if a compound of formula (II) is obtained in step a), deprotecting said compound to produce Estetrol.