A method of preparation of oxycodone

It discloses a method of preparation of Oxycodone of formula I by reaction of thebaine of formula II, or its analogue of formula III, wherein R is alkyl having a carbon number C.sub.2.n. to C.sub.5.n., alkylaryl such as benzyl, nebomethoxybenzyl or allyl, with hydrogen peroxide or peroxoacids in the presence of oxalic acid in admixture with acetic acid or formic acid. From the resulting crystalline precipitate of 14-hydroxycodeinone by adding bázeuvolní 14-hydroxycodeinone of formula IV, which is hydrogenated with hydrogen in the presence of a catalyst to yield Oxycodone of formula I. Oxycodone is transformed into hydrochloride, which is used as active substance in analgesic compositions.