A process for the preparation of a hydroxybenzaldoxime O-ether of the formula ##STR1## in which R.sup.1 is alkyl, alkenyl or alkinyl, comprising reacting an aminobenzaldoxime O-ether of the formula ##STR2## in which R.sup.1 has the abovementioned meaning, with a diazotizing agent in acidic, aqueous solution, and thermally hydrolyzing the resulting diazonium salt of the formula ##STR3## in which X.crclbar. in an equivalent of an inorganic anion andR.sup.1 has the abovementioned meaning,in acidic, aqueous solution without intermediate isolation.The products are intermediates for agricultural and pharmaceutical chemicals.Novel amino-benzaldoxime O-ethers of the formula ##STR4## wherein R.sup.1 has the above-mentioned meaning.