A process for the preparation of a hydroxybenzaldoxime O-ether of the formula ##STR1## in which R.sup.1 represents alkyl, comprising(a) in a first step, hydrogenating a nitro-benzaldoxime O-ether of the formula ##STR2## using the calculated amount of hydrogen in the presence of a catalyst and in the presence of a diluent, and(b) in a second step, reacting the amino-benzaldoxime O-ether of the formula ##STR3## thus obtained with a diazotizing agent in acidic, aqueous solution, and, without isolation, thermally hydrolyzing the resultant diazonium salt of the formula ##STR4## in which X.crclbar. represents an equivalent of an inorganic anion, in acidic, aqueous solution.