Obtaining reliable kinetic parameters for radical-radical reaction channels from theoretical calculations is difficult, as they are barrierless, and the radical-radical interaction potential in the transition state region exhibits strong multireference electronic character. Furthermore, a number of the modes are strongly coupled with significant deviation from harmonic oscillator behavior. The prediction of the pressure dependence is complicated by the dependence on thermochemical data and energy transfer parameters. Experimental kinetics data are sparsely available for radical-radical pathways due to the challenges of generating and monitoring radicals and the complications of secondary reactions. As a result, the experimental data that are available often display high uncertainty.