A process for producing noroxymorphone from morphine wherein morphine is reacted to a compound of formula (Va) or (Vb), wherein R 1, and R 1' independently are a substituted or unsubstituted alkyl group with 1 to 20 carbon atoms or a substituted or unsubstituted aryl group, or a substituted or unsubstituted alkenyl group having 2 to 20 carbon atoms, or a substituted or unsubstituted carbonyloxyalkyl group with 1 to 20 carbon atoms in the alkyl residue, or a substituted or unsubstituted carbonyloxyaryl group or a substituted or unsubstituted carbonyloxyalkylaryl group with 1 to 20 carbon atoms in the alkyl residue, or a silylgroup of formula Si(R 4) 3, wherein the groups R 4 can be the same or different and are each selected from substituted or unsubstituted alkyl groups having 1 to 6 carbon atoms and unsubstituted or substituted phenyl groups, respectively, and wherein R 2 is a substituted or unsubstituted aliphatic or aromatic acyl group with 1 to 20 carbon atoms, wherein the compound of formula (Va) or (Vb) is reacted to a compound of formula (VIa) or (VIb), respectively, and the compound of formula (VIa) or (VIb) is then reacted to noroxymorphone; wherein the reaction of the compound of formula (Va) or (Vb) to the compound of formula (VIa) or (VIb) is carried out with hydrogen peroxide and an organic acid, wherein the organic acid and the hydrogen peroxide are mixed and allowed to react for a defined induction time prior to addition to the compound of formula (Va) or (Vb), the process for producing noroxymorphone comprising the following further steps: (i) reacting morphine of formula to a compound of formula (IIIa) or (IIIb), wherein R 1 and R 1' independently are a substituted or unsubstituted alkyl group with 1 to 20 carbon atoms or a substituted or unsubstituted aryl group, or a substituted or unsubstituted alkenyl group having 2 to 20 carbon atoms, or a substituted or unsubstituted carbonyloxyalkyl group with 1 to 20 carbon atoms in the alkyl residue, or a substituted or unsubstituted carbonyloxyaryl group or a substituted or unsubstituted carbonyloxyalkylaryl group with 1 to 20 carbon atoms in the alkyl residue, or a silylgroup of formula Si(R 4) 3, wherein the groups R 4 can be the same or different and are each selected from substituted or unsubstituted alkyl groups having 1 to 6 carbon atoms and unsubstituted or substituted phenyl groups, respectively; (ii) reacting the compound of formula (IIIa) or (IIIb) to a compound of formula (IVa) or (IVb), respectively; (iii) reacting the compound of formula (IVa) or (IVb) to a compound of formula (Va) or (Vb), respectively; (v) reacting the compound of formula (VIa) or (VIb) to a compound of formula (VIIa) or (VIIb), respectively; and (vi) reacting the compound of formula (VIIa) or (VIIb) to noroxymorphone of formula, respectively, wherein step (ii) is conducted using a Swern oxidation with pre-cooled solutions. (i) reacting morphine of formula to a compound of formula (IIIa) or (IIIb), wherein R 1 and R 1' independently are a substituted or unsubstituted alkyl group with 1 to 20 carbon atoms or a substituted or unsubstituted aryl group, or a substituted or unsubstituted alkenyl group having 2 to 20 carbon atoms, or a substituted or unsubstituted carbonyloxyalkyl group with 1 to 20 carbon atoms in the alkyl residue, or a substituted or unsubstituted carbonyloxyaryl group or a substituted or unsubstituted carbonyloxyalkylaryl group with 1 to 20 carbon atoms in the alkyl residue, or a silylgroup of formula Si(R 4) 3, wherein the groups R 4 can be the same or different and are each selected from substituted or unsubstituted alkyl groups having 1 to 6 carbon atoms and unsubstituted or substituted phenyl groups, respectively; (ii) reacting the compound of formula (IIIa) or (IIIb) to a compound of formula (IVa) or (IVb), respectively; (iii) reacting the compound of formula (IVa) or (IVb) to a compound of formula (Va) or (Vb), respectively; (v) reacting the compound of formula (VIa) or (VIb) to a compound of formula (VIIa) or (VIIb), respectively; and (vi) reacting the compound of formula (VIIa) or (VIIb) to noroxymorphone of formula, respectively, wherein step (ii) is conducted using a Swern oxidation with pre-cooled solutions.