Acetic acid ethyl ester is prepared by passing ethylene over a fixed-bed catalyst composed of silicon dioxide, which has a surface from 50 to 200 m.sup.2 /g and which is impregnated with H.sub.2 SO.sub.4, diethylsulfate or ethylsulfuric acid or mixtures of these compounds, with periodically alternating quantities of acetic acid, at a temperature from 130.degree. to 170.degree. C, the acid concentration, calculated on ethylene, varying constantly over a range from 0.01 to 40% by mole.