XE-60 afforded the best resolution between the trimethylsilyl (TMS) derivatives of a monosaccharide mixture containing arabinose, xylone, mannose, galactose and glucose. Critical resolutions involved certain isomers of (a) xylone and mannose, and (b) galactose and glucose. Resolution between the xylone and mannose isomers was related to the liquid phase concentration and complete resolution could be achieved by concentrations of 1.0-1.2% XE-60. Resolution between the galactose and glucose isomers at the liquid phase concentrations was markedly influenced by the solid support and an apparent consequently influence on the number of theoretical plates of the column. This resolution was markedly improved when dimethylchlorosilanetreated Chromosorb W, as compared to a non-silanized Chromosorb W, was used. The relative retention time and approximate isomers abundance for a number of the other monosaccharide TMS derivatives is reported. © 1969.