The crossed molecular beam reactions of the meta-tolyl radical with 1,3-butadiene and D6-1,3-butadiene were conducted at collision energies of 48.5 kJ mol−1 and 51.7 kJ mol−1. The reaction dynamics propose a complex-forming reaction mechanism via addition of the meta-tolyl radical with its radical center either to the C1 or C2 carbon atom of the 1,3-butadiene reactant forming two distinct intermediates, which are connected via migration of the meta-tolyl group. Considering addition to C1 proceeds by formation of a van-der-Waals complex below the energy of the separated reactants, we propose that in cold molecular clouds holding temperatures as low as 10 K, the reaction of the meta-tolyl radical with 1,3-butadiene is de-facto barrier less. At elevated temperatures such as in combustion processes, the reaction can also proceed via addition to C2 by overcoming the entrance barrier to addition (11 kJ mol−1). Eventually, the resonantly stabilized free radical intermediate C11H13 undergoes isomerization to a cis fo