More acidic sulfated metal oxides (SMO) such as SO42-/ZrO2 and SO42-/TiO2 catalyzed the methoxymethylation of alcohols with dimethoxymethane at ambient temperature to achieve a product yield of greater than 90% within a few hours. The reaction displayed a significant steric effect on the product yield with a preferential order of primary alcohol> secondary alcohol >> tertiary alcohol. The observed steric effect might result from the repulsion between the bulky alkyl group in the alcohol and the two methoxy groups in the protonated dimethoxymethane (oxonium ion).