Two kinds of 1,2,3,4-butanetetracarboxylic acid type gemini surfactants having semifluoroalkyl groups (Rf-(CH 2 ) n -; Rf = C 8 F 17 , n = 2,3,4,5,6,8,11) as diester of 2,3-bis-COOH and 1,4-bis-COOH were prepared from 1,2,3,6-tetrahydrophthalic anhydride as the key material. Their surface properties were studied by surface tension and surface pressure-area (π–A) measurements. Semifluoroalkylated geminis showed excellent surface tension re-ducing ability, but the values of the critical micelle concentration (CMC) and γ CMC remained nearly unaffected by the methylene chain length. From the zero-pressure molecular areas of semifluoro-alkylated geminis and the compression modulus analysis, it was clarified that semifluoroalkylated gemini surfactants having short methylene chains would form more rigid monolayers than those having long methylene chains. But, there were not very large differences in surface properties between two geminis having the same methylene chain length.