Nickel atoms are injected into the Earth's mesosphere by meteoric ablation, producing a Ni layer between 70 and 105 km in altitude. The subsequent reactions of Ni and NiO with atmospherically relevant species were studied using the time-resolved pulsed laser photolysis-laser induced fluorescence technique, combined with electronic structure calculations and RRKM theory where appropriate. Results for bimolecular reactions (in cm(3) molecule(-1) s(-1) ): k(Ni + O-3, 293K) = (6.5 +/- 0.7) x10(-10) ; k(NiO + O-3 -> Ni + 2O(2), 293 K) = (1.4 +/- 0.5) x 10(-10); k(NiO + O-3 -> NiO2 + O-2, 293 K) = (2.5 +/- 0.7) x 10(-10); k(NiO + CO, 190-377 K) = (3.2 +/- 0.6) x 10(-11) (T/200)(-0.19 +/- 0.05). For termolecular reactions (in cm(6) molecule(-2) s(-1), uncertainty +/-sigma over the stated temperature range): log(10)(k(rec,0)(Ni + O-2 + N-2, 190-455 K)) = -37.592 + 7.168log(10)(T) - 1.5650(log(10)(T))(2), sigma = 11%; log(10)(k(rec,0)(NiO + O-2 + N-2, 293-380 K)) = -41.0913 + 10.1064log(10)(T) - 2.2610(log(10)(T))(2), sigma = 22%; and log(10)(k(rec,0)(NiO + CO2 + N-2, 191-375 K)) = -41.4265 + 10.9640log(10)(T) - 2.5287(log(10)(T))(2), sigma = 15%. The faster recombination reaction NiO + H2O + N-2, which is clearly in the fall-off region over the experimental pressure range (3-10 torr), is best described by: log(10)(k(rec,0)/cm(6) molecule(-2) s(-1)) = -29.7651 + 5.2064log(10)(T) - 1.7118(log(10)(T))(2), k(rec),(infinity) = 6.0 x 10(-10) exp(-171/T) cm(3) molecule(-1) s(-1), broadening factor F-c = 0.84, sigma = 16%. The implications of these results in the atmosphere are then discussed.