The 2,6-di-tert-butyl-4-methoxy-phenoxyl radical is shown to dimerize in solution and in the solid state. The X-ray crystal structure for the dimer, the first for a para-coupled phenoxyl radical, reveals a bond length of 1.6055(23) Å for the 4-4’ C–C bond. This is significantly longer than typical C–C bonds. Solution equilibrium studies using both optical and IR spectroscopies show that the Keq for dissociation is 1.3 ± 0.2 M at 20 °C, indicating a C–C bond dissociation free energy of −0.15 ± 0.1 kcal mol−1. Van’t Hoff analysis gives an exceptionally small bond dissociation enthalpy (BDE) of 6.1 ± 0.5 kcal mol−1. To our knowledge, this is the weakest BDE measured for a C–C bond. This very weak bond shows a large deviation from the correlation of C–C bond lengths and strengths, but the computed force constant follows Badger’s rule.