Steady-state linear laser induced fluorescence (LIF) has been used to investigate internal energy redistribution rates in A 2 Δ v′ = 0 CH in a low pressure oxyacetylene flame. By obtaining rotationally resolved spectra as a function of pressure the branching ratio, defined as the ratio of rotational transfer ( R) out of the laser excited state divided by the electronic quenching rate ( Q), was measured for a variety of flame conditions. For a stoichiometric 1600K flame and K′ = 6 excitation R Q = 3.6 ± 0.5 . The branching ratio was also found to increase with K′ and decrease with equivalence ratio. In addition, for K′ = 6 excitation, a value of the electronic quenching cross section of 5.4 ± 3.6 Å 2 was obtained.