Process for the preparation of alpha, beta unsaturated aldehydes by oxidation of alcohols in the presence of a liquid phase wherein the liquid phase contains 0.1 to less than 25 weight-% water and wherein the liquid phase contains at least 25 weight-% of alcohol(s) of general formula (II) and alpha, beta unsaturated aldehyde(s) of general formula (I) and wherein the oxidant is oxygen and/or hydrogen peroxide.