An environmental chamber/Fourier transform infrared system was used to determine the rate coefficient k1 for the gas-phase reaction of OH with 2-methyl-3-buten-2-ol (MBO, (CH3)2C(OH)CH=CH2), relative to the rate of its reaction with ethylene (k2) and propylene (k3). Experiments performed at 295¿1 K, in 700 torr total pressure of air, gave k1=(6.9¿1.0)¿10-11 cm3 molecule-1 s-1. At 295¿1 K, the reaction of OH with MBO yielded, on a per mole basis, (52¿5)% acetone, (50¿5)% glycolaldehyde, and (35¿4)% formaldehyde. The production of acetone from the oxidation of MBO may be of significance globally. The kinetics and mechanism of the reaction of chlorine atoms with MBO (k15) have also been studied at 700 torr total pressure of air and 295¿1 K. The rate coefficient was determined using a relative rate technique, with ethane (k16), ethylene (k17), and cyclohexane (k18) as reference compounds. The value of k15 was found to be (3.3¿0.4)¿10-10 cm3 molecule-1 s-1 at 295 K. The major carbon-containing products obtained in the Cl-atom oxidation of MBO were acetone (47¿5)%, chloroacetaldehyde (53¿5)%, HCOCl (<11%), and formaldehyde (6¿2)%. ¿ 1998 American Geophysical Union