In this work, novel SO 3 H type Gemini surfactants having semifl uoroalkyl group (RfCH 2 CH-: Rf = C 4 F 9 , C 6 F 13 , C 8 F 17 ) as hydrophobic group were successively synthesized by the radical addition of fl uoroalkyl to 1,4-pentadiene using fl uoroalkyl iodide and AIBN as initiator, and the following thiocyanization (-SCN), conversion to -SH, and oxidation to SO 3 H as hydrophilic group. Similarly, the common 1+1 type semifl uoroalkyl surfactants having SO 3 H were synthesized.Surfactant properties of their sodium salts (cmc, γ cmc, pC 20 , Γ cmc , and A) were investigated by measuring surface tension. As expected, the cmc value of Gemini surfactant whose fl uoroalkyl is C 4 F 9 was more than one order of magnitude smaller than that of the corresponding 1+1 type. Other properties also showed the excellent effi ciency of Gemini structure to reduce the surface tension.