Abstract: New, cationically curable oxyalkylene ethers and the synthesis thereof are disclosed. The oxyalkylene ethers, are of the general, average formula ##STR1## wherein R.sup.1 is an n-valent residual group derived from a compound (R.sup.1)H.sub.n from which n active hydrogen atoms have been split off and is capable of entering into an addition reaction with oxiranes, or a univalent alkyl or aryl group, and n.gtoreq.1;R.sup.2 is a hydrogen, hydrocarbon or R.sup.3 OCH.sub.2 -- group;R.sup.3 and R.sup.4 are each hydrogen, hydrocarbon or acyl groups, and R.sup.1, R.sup.2, R.sup.3 and R.sup.4 may have different meanings in the molecule;R.sup.5, R.sup.6 and R.sup.7 are each hydrogen or alkyl groups with 1 to 8 carbon atoms, or R.sup.5 and R.sup.7, or R.sup.6 and R.sup.7 together are a constituent of a cyclic, non-aromatic hydrocarbon group with 5 or 6 carbon atoms;m is at least 1 and at most n;x is the average molecule=3 to 100, andy in the average molecule=0 to 100, provided that 3.ltoreq.x+y<150.