A simple, general and efficient method has been developed for the conversion of aldehydes to 1,1-diacetates using acetic anhydride, a catalytic amount of non commercial Keggin heteropolyacid (H<SUB>6</SUB> PalMo<SUB>11</SUB>O<SUB>40</SUB>) (1% mol) in solvent free conditions at room temperature. Aromatic and aliphatic, simple and conjugated aldehydes were protected with excellent yields.Facultad de Ciencias Exactas