The kinetics of the reaction of hydroxyl radical with 1,3-butadiene at 240-340 K and a total pressure of similar to 1 Torr has been studied using relative rate combined with the discharge flow and mass spectrometer technique. The reaction dynamics of the same reaction has also been investigated using ab initio molecular orbital theory. The rate constant for this reaction was found to be negatively dependent on temperature, with an Arrhenius expression of k(1) = (1.58 +/- 0.07) x 10(-11) exp[(436 +/- 13)/T] cm(3) molecule(-1) s(-1) (uncertainties taken as 2 sigma), which was in good agreement with that reported by Atkinson et al.(21) and Liu et al.(22) at 299-424 K. Mass spectral evidences were found for the addition of OH to both the terminal and the internal carbons of 1,3-butadiene. Our computational results suggest that both addition of CH to 1,3-butadiene and the abstraction of hydrogen atom from 1,3-butadiene by the OH radical are exothermic processes and that the addition of OH to the terminal carbon of the 1,3-butadiene is predicted to have an activation energy of 0.7 kcal mol(-1), being the most energetically favored reaction pathway.