The reaction mechanism of OH radicals with CH 2 CHCH 2 CH 2 OH on the ground electronic state has been studied at the QCISD(T)/6-311++G(d,p) level of theory based on the geometric parameters optimized at the MP2(full)/6-311G(d,p) level of theory. Two types of reactions including the hydrogen abstraction and the addition–elimination reaction have been considered. The calculational results indicate that the formations of IM1(CH 2 (OH)CHCH 2 CH 2 OH) and IM2 (CH 2 CH(OH)CH 2 CH 2 OH) in the addition process via van der Waals complex PC3 will be more favorable than the abstraction reactions at room temperature. The formations of P20 (HCHO+CH 3 CH(OH)CH 2 ) and P19 (CH 3 CHOH+CH(OH)CH 2 ) initiated from IM2 will be the most favorable reaction paths, whereas the hydrogen abstraction products of P6 (CH 2 CHCH 2 CHOH(I))+H 2 O via indirect mechanism and the dissociation products of P11 (CH 2 CH 2 CH 2 OH+HCHO) via TS7–P11 initiated from IM1 will be the minor ones.