A new solid phase method for hydrolysis of acetyl groups from the intermediate 2-[18F]fluoro-2-deoxyglucose tetraacetate ([18F]FDG-Ac4) was developed. Fast cleavage occurs with Dowex 50 sulfonic acid resin (H+ form) at approximately 100 degrees C in the absence of bulk water. [18F]FDG-Ac4 reaction mixtures were efficiently converted to neutral aqueous solutions of pure FDG in 10-15 min. The method avoids problems associated with liquid acids and can be easily integrated into existing [18F]FDG procedures.