The hydroxycarbonyl products formed from the gas-phase reactions of 1,2-, 1,3-, and 2,3-butanediol and 2-methyl-2,4-pentanediol have been investigated using solid-phase micro extraction fibers coated with the derivatizing reagent O-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine hydrochloride. Following on-fiber derivatization of carboryl-containing products, they were analyzed by subsequent thermal desorption and gas chromatography with flame ionization detection (GC-FID) and combined gas chromatography-mass spectrometry. In addition to the hydroxyketone products previously observed by gas chromatography without prior derivatization, the hydroxyaldehyde products observed as their oximes were CH3CH2CH(OH)CHO and HOCH2CHO from 1,2-butanediol; CH3CH(OH)CH2CHO, HOCH2CHO, and CH3CH(OH)CHO from 1,3-butanediol; CH3CH(OH)CHO from 2,3-butanediol; and CH3CH(OH)CHO from 2-methyl-2,4-pentanediol. These hydroxyaldehydes were quantified using estimated GC-FID response factors developed for on-fiber derivatization sampling, and the observed hydroxycarbonyl products account for 71-103% of the reaction pathways for these four diols. The reaction products, and their formation yields, predicted from mechanisms based on the literature database for reactions of OH radicals with volatile organic compounds, agree with our experimental data.