Abstract: Process for preparing an alkoxylated alcohol comprising reacting a starting monohydroxy alcohol selected from secondary alcohols, tertiary alcohols and mixtures thereof with an alkylene oxide in the presence of hydrogen fluoride and a boron-containing compound comprising at least one B—O bond. The alcohol may also be a primary monohydroxy alcohol when the boron containing compound is boric acid or boric acid anhydride or a mixture thereof, or may be a primary mono hydroxy alcohol, except a C14/C15 alcohol when reacted with ethylene oxide in the presence of HF and trimethyl borate. A phenol may be alkoxylated in the same way instead of the mono-hydroxyalcohol.