Abstract: There are three different chemical structures in methyl tertiary hexyl eTher (MTHE) isomeric compounds. Their EI mass spectra were not reported in the reference books and literatures including the latest Wiley Registry of Mass Spectral Data (13.SK). In this paper, the ElMS spectra of three MTHE isomeric compounds were obtained and their chemical structures were identified by GC/MS technique and Their retention behavior of chromatography.