Absolute rate coefficients for the title reaction, HO + HOCH₂C(O)CH₃ → products (R1) were measured over the temperature range 233–363 K using the technique of pulsed laser photolytic generation of the HO radical coupled to detection by pulsed laser induced fluorescence. The rate coefficient displays a slight negative temperature dependence, which is described by: k₁(233–363 K) = (2.15 ± 0.30) × 10⁻¹² exp{(305 ± 10)/T} cm³ molecule⁻¹ s⁻¹, with a value of (5.95 ± 0.50) × 10⁻¹² cm³ molecule⁻¹ s⁻¹ at room temperature. The effects of the hydroxy-substituent and hydrogen bonding on the rate coefficient are discussed based on theoretical calculations. The present results, which extend the database on the title reaction to a range of temperatures, indicate that R1 is the dominant loss process for hydroxyacetone throughout the troposphere, resulting in formation of methylglyoxal at all atmospheric temperatures. As part of this work, the rate coefficient for reaction of O(³P) with HOCH₂C(O)CH₃ (R4) was measured at 358 K: k₄(358 K) = (6.4 ± 1.0) × 10⁻¹⁴ cm³ molecule⁻¹ s⁻¹ and the absorption cross section of HOCH₂C(O)CH₃ at 184.9 nm was determined to be (5.4 ± 0.1) × 10⁻¹⁸ cm² molecule⁻¹.