The absolute third-order rate constant for the recombination between Cs + O2 + Nz was studied by time-resolved atomic resonance absorption spectroscopy following pulsed irradiation of CsCl vapour at elevated temperatures. CS(~~S,,~), generated on photolysis, was monitored photoelectrically in absorption in the "single-shot mode" using the spin-orbit resolved Rydberg transition at x = 455.5 nm (Cs(?'p(*P,,,)) + CS(SS(~S,,,))). These photoelectric signals were captured, digitized and stored in a transient recorder, employed in the "A/B" mode, and were transferred directly to a microcomputer for kinetic analysis. Decay profiles for the caesium atom were recorded in the presence of N2 alone in order to characterize the diffusional loss of the atom (a necessary component of the kinetic study) and in the presence of O2 + N,. A diffusion coefficient of D(Cs-N,, s.t.p.) = 0.22 + 0.07 cm2 s-l was obtained. The third-order rate constant for the effective single temperature of T = 827 f 13 K is k(Cs + O2 + N,) = (2.01 + 0.67) X 10Y3' cm6 molecule-2 s-'. This result is subject to the standard Trije unimolecular extrapolation to yield the form ln(k,,,, o ( cm6 moleculeY2 s-l)) = (-0.2165 f 0.00382) (In T (K))2 + (1.0175 + 0.05) ln(T (K)) -65.45 + 0.16. The results are compared with previous kinetic data for Cs + O2 + Ar obtained from resonance ionization spectroscopy and Cs + O2 + M obtained in flame environments.