A process for the preparation of a heteroaryloxyacetamide of the formula ##STR1## in which R is a 5 membered heterocycle which may be benzo-fused, andR.sup.1 and R.sup.2 each independently is hydrogen, alkyl, alkenyl, alkynyl, cycloalkyl or cycloalkenyl, halogenoalkyl, alkoxyalkyl, alkoxy, aralkyl or aryl, orR.sup.1 and R.sup.2, together with the nitrogen atom to which they are bonded, form a heterocycle,which comprises reacting a sulphonylated heteroaromatic of the formulaR--SO.sub.2 --R'in whichR' is lower alkyl or benzyl,with an .alpha.-oxyacetamide of the formula ##STR2## in which R" is hydrogen or acyl,in the presence of an inorganic base as an acid acceptor and of solvent as a diluent at a temperature of about -50.degree. C. to +150.degree. C. The products are known herbicides.