The quaternary ammonium reagent m-(trifluoromethyl)phenyltrimethylammonium hydroxide (TMTFTH) has gained widespread use for the derivatisation for GCMS analysis of organic materials found in artists' materials, such as oils, plant resins and waxes. This paper discusses products formed from reactions of TMTFTH with alcohols--including fatty alcohols, hydroxyacids, terpenes and glycerol--that have diagnostic value in the analysis of samples from artworks. In addition to methyl ethers, (trifluoromethyl)phenyl ethers were formed to variable degrees from the different types of alcohol. The products were identified from their EI mass spectra. An understanding of these multiple reaction products is important for the interpretation of GCMS data from complex samples, especially in the case of polyfunctional alcohols such as glycerol, which forms a number of methyl, (trifluoromethyl)phenyl and mixed ethers. The significance of the reaction products, and the relative advantages of TMTFTH as compared to alternative ammonium and sulfonium methylating reagents, are discussed.