2-(1,1-dicyanopropen-2-yl)-6-(2-[18F]-fluoroethyl)-methylamino-naphthalene ([18F]FDDNP) was synthesized in a single step labeling procedure. The precursor, 2-(1,1-dicyanopropen-2-yl)-6-(2-tosyloxyoethyl)-methylamino-naphthalene, was fluorinated with 18F in acetonitrile. After 15 min the reaction mixture was subjected to preparative HPLC purification. The product was isolated from the HPLC eluent with solid-phase extraction, and formulated in an ascorbic acid solution to prevent formation of side products during formulation. Quantitative sticking to tubing and filters was overcome by the addition of polysorbatum-80. This formulation yielded an isotonic, pyrogen-free and sterile solution of [18F]FDDNP. The overall decay-corrected radiochemical yield was 41+/-11% (n=22). Radiochemical purity was >98% and the specific activity was 102+/-56 GBq/micromol at the end of synthesis.