A flnoroalkylbonded phase used.as HPLC packing has been prepared from silica (5μ) and 1, 1, 2, 2-tetrahydro-7 trifluoromethyldodecaflnorooctyltrichloro-ailane, (CF₃)₂CF (CF₂)₄CH₂CH₂SiCL₃.By controlling the surface concentration of the organic ligand, we prepared the packing which may be need either in normal phase or in reverse phase mode.Comparing with the perfluoroamide bonded phase packing previously prepared by us, it not only has the same chromatographio performance to give a much shorter retention time for polar ateroidal compounds, to improve the peak symmetry and reduce tailing, bnt also more hydrophobic and leas polar in nature.This fluoroalkyl bonded phase packing gives a good separation in nonaqneons reverse phase mode towards some choleric acids which formerly can only be separatedtion exchange or reverse phase chromatography and show severe tailing on ciliagel column.On the other hand, the separation of phenols and polyhydroxy steroids are also anccesaful on thin column in reverse phase mode.