Polymer-immobilized fluorinase for the synthesis of 5′-fluoro-5′-deoxyadenosine (FDA) from S-adenosyl-l-methionine (SAM) and fluoride ion in aqueous media is described. The optimal composition of the poly(glycidyl methacrylate-co-ethylene glycol dimethacrylate) and the heterogeneous catalytic reaction conditions were developed to yield FDA in 49% within 150 min. In PET radiochemistry, using [18F]fluoride ion in [18O]H2O obtained from the cyclotron, [18F]FDA was synthesized with 68% fluorination efficiency. The immobilized fluorinase was recycled for up to four runs with 80% of catalytic activity in the final cycle.