Recently the mass spectra of simple α-hydroxy-ketones were reported to contain peaks arising from isomeric ketols attributed to electron impact-induced 1,2-alkyl migrations. These peaks have now been shown to be an artifact of thermal rearrangements in the inlet systems. The mass spectra of simple tertiary ketols from A.E.I. model MS-9 and Finnigan model 1015 mass spectrometers are compared and contrasted.