High pressure,as the most efficient way to reduce the intermolecular distances,has been the subject of intensive research in various fields.1 Pressure-induced behavior of aromatic compounds recently attracts great interests because of their importance in constructing new dense carbon materials.2 Preliminary high pressures studies on hexafluorobenzene(C6F6),a perfluorinated aromatic molecule was investigated by in situ Raman,IR,and XRD spectroscopies,which verified the occurrence of compression-induced phase transitions and polymerization under extreme conditions.However,owing to the complexity of polymeric products(sometimes decades of compounds may be contained),the molecule structural information is still not unambiguous.Mass spectrometry,as the only way to measure the exact mass of samples,could be applied to pure samples as well as complex mixtures when combined with chromatographic columns.Herein,we exploit high resolution gas chromatography-mass spectrometry(GC-MS)to analyze the target samples,which takes advantages of full scan mode,quick scan rates,high resolution and high sensitivity.The obtained mass spectrum indicates that a series of hexafluorobenzene polymer with formula(C6F6)n(n≧2)are formed under high pressures,which provide a direct evidence of compression-induced polymerization of C6F6.Further analysis on the molecular structure of polymeric products of C6F6 is ongoing,which would greatly helps to elucidate the reaction mechanism under high pressure conditions.