Disclosed herein is a process for the preparation of morphine compounds comprising a low content of á,â-unsaturated compounds, comprising the steps of: (i) bringing the crude morphine compound into contact with a base, at a pH of greater than 13, under conditions which make possible the Michael addition reaction on the á,â-unsaturated compound(s) present (ii) separating the morphine compound from the reaction mixture and (iii) if appropriate, separating the addition product formed from the morphine compound. Also disclosed is a composition comprising at least 99% by dry weight of morphine compound produced according to the process as described above, and an á,â-unsaturated compound in a content of less than 100 ppm and additionally comprising at least one compound resulting from an aldol condensation reaction occurring in the process according to at least the process defined above or at least one compound resulting from a crotonization reaction occurring in the process according to at least the process defined above.
