Oligo-ethylene/propylene glycol ethyl ether acetate (oligo-EGEEA and oligo-PGEEA) used to be synthesized in a two-step process with acetic acid as starting material. This paper describes a one-step production process catalyzed by the Al-Mg composite oxide, achieved by alkoxylation of ethyl acetate directly. Aiming at a narrow adduct distribution to get high product selectivity of mono-derivatives, the alkoxylation parameters, such as the Al/Mg molar ratio of the catalyst, molar ratio of reactants, temperature, initial reaction pressure, and reactant feed rate were investigated. The highest content of mono- and di-derivatives in the products was: W (oligo-EGEEA) = 73.8%, omega (oligo-PGEEA) = 87.9%, respectively. The product selectivity of mono-EGEEA was decreased by only 5% after reusing the catalyst for ten runs. A 1.26-fold increase in the yield of mono-PGEEA was achieved by treating the catalyst surface with alcoholic potash. (c) 2006 Society of Chemical Industry