In April 1988, five panels by A. Dürer at the Alte Pinakothek, Munich, were damaged by an act of vandalism. Large areas of the paint layers, the ground, and even the wooden support were severely affected by concentrated sulfuric acid. This contribution discusses first measures taken after the attack. Possible chemical reactions between the painting materials and the acid are identified. The analytical results allow reevaluation of the conventional adsorption and neutralization procedures so far applied. An alternative treatment with a specially conditioned ion-exchange resin is proposed. Its application turned out to be very effective in softening the crusts, adsorbing acid reaction products as well as neutralizing the remaining parts. The preparation and the handling of the ion-exchange resin are discussed in detail.