Abstract: Carbon-14 labelled Dufulin, diethyl ((2-fluorophenyl)((4-methylbenzo2-14Cthiazol-2-yl) amino)methyl)phosphonate was synthesized from barium 14Ccarbonate via Grignard reaction, Curtius arrangement, nucleophilic addition, thionation reaction, cyclization reaction, etc. The labelled product (38.3 mCi) was obtained after RP-HPLC purification in the overall radiochemical/chemical yield of 10%. The product was characterized by ESI-MS, 1H NMR and HPLC-FSA. Its technical data (radiochemical purity > 98%, chemical purity > 98%, specific activity 58.0 mCi/mmol) was determined by TLC-IIA, HPLC-LSC, HPLC-FSA/PDA/MS and LSC. This carbon-14 labelled Dufulin can be used as radiotracer in the study on its metabolism and environmental behavior by employing radioisotope tracing techniques.