The rhenium–methyl bond cleavage in CH₃ReO₃ has been investigated by means of quantum chemical calculations of the one-D potential energy surfaces (PES) associated to the low-lying singlet and triplet excited states of the molecule. The quantum dynamics is studied by wave packet propagations on the b¹A₁ absorbing state coupled non-adiabatically to the low-lying a¹E state. The spin–orbit states and spin–orbit couplings are evaluated according to the zeroth-order regular approximation (ZORA). The spin–orbit coupling between the a¹E state and the a³A₁ dissociative state controls the radical formation ˙CH₃ + ˙ReO₃, which occurs in 400 fs.