Three skeletal rearrangement channels for the norbornadiene (N˙⁺) to the 1,3,5-cycloheptatriene (CHT˙⁺) radical cation conversion, initialized by opening a bridgehead-methylene bond in N˙⁺, are investigated using the quantum chemical B3LYP, MP2 and CCSD(T) methods in conjunction with the 6–311+G(d,p) basis set. Two of the isomerizations proceed through the norcaradiene radical cation (NCD˙⁺), either through a concerted path (N˙⁺ – NCD˙⁺), or by a stepwise mechanism via a stable intermediate (N˙⁺ – I1 – NCD˙⁺). At the CCSD(T)/6–311+G(d,p)//B3LYP/6–311+G(d,p) level, the lowest activation energy, 28.9 kcal mol⁻¹, is found for the concerted path whereas the stepwise path is found to be 2.3 kcal mol⁻¹ higher. On both pathways, NCD˙⁺ rearranges further to CHT˙⁺ with significantly less activation energy. The third channel proceeds from N˙⁺ through I1 and then directly to CHT˙⁺, with an activation energy of 37.1 kcal mol⁻¹. The multi-step channel reported earlier by our group, which proceeds from N˙⁺ to CHT˙⁺via the quadricyclane and the bicyclo[2.2.1]hepta-2-ene-5-yl-7-ylium radical cations, is 4.6 kcal mol⁻¹ lower than the most favorable path of the present study. If the methylene group is substituted with C(CH₃)₂, however, the concerted path is estimated to be 5.6 kcal mol⁻¹ lower than the corresponding substituted multi-step path at the B3LYP/6–311+(d,p) level. This shows that substitution of particular positions can have dramatic effects on altering reaction barriers in the studied rearrangements. We also note that identical energies are computed for CHT˙⁺ and NCD˙⁺ whereas, in earlier theoretical investigations, the former was reported to be 6–17 kcal mol⁻¹ more stable than the latter. Finally, a bent geometry is obtained for CHT˙⁺ with MP2/6–311+G(d,p) in contradiction with the planar conformation reported for this cation in earlier computational studies.