SiOC-bonded polyether siloxanes are produced by transesterification of alkoxysiloxanes with polyetherols in the presence of trifluoromethanesulfonate as catalyst. The computational total water content of the reactants including alkoxysiloxanes and polyetherols is ≤5000 ppm by mass, advantageously ≤300 ppm by mass, preferably ≤150 ppm by mass, more preferably ≤100 ppm by mass, in particular ≤50 ppm by mass. The determination of the individual water contents is performed beforehand, preferably by titration according to Karl Fischer.