The invention relates to a process for preparing alkylpolyglycosides from monomeric glycosides, oligo- or polyglycosides and alcohols according to the general scheme (Glyc-O).sub.zH+R.sup.1--OH.fwdarw.(Glyc-O).sub.z'R.sup.1 where z.gtoreq.1, z'.ltoreq.z, preferably from 1 to 10, (Glyc-O)-- is a glycoside radical, R.sup.1 is a hydrocarbon radical which optionally contains multiple bonds and/or heteroatoms, which comprises carrying out the reaction under supercritical conditions with regard to the alcohol, preferably at pressures and temperatures which are at least 5% above the critical parameters, the alcohols serving both as the solvent and as reactants.