A theoretical study was performed to investigate the probable fragmentation channels of a singly charged ethanol radical to represent the signals of m/ e 45, 31, 44, 32, 30 and 28, found in the related mass spectra. The related fragments as implied in the mass spectra should originate from conformers of CH 3CH 2OH + through the H-elimination channels. In order to obtain reasonable rate constants, it is necessary to include the anharmonic frequencies in RRKM method to eliminate the unrealistic rotational mode in the transition state. Most of the C 2H 6O + isomerization reactions require more energy than the abstraction of methyl group and hydrogen atom from CH 3CH 2OH +. Consistent with experimental observation, at low energy, the H-abstraction channels are preferred due to the low energy barriers, while, at high energy, and the methyl abstraction channels are dominated. The fragments with formation energy barriers from high to low are CH 2 CH 2 + , CH 2O +, CH 2CHOH + and CH 2 OH 2 + accordingly, also in a good agreement with experimental observation.