Abstract Resolved flame emission spectra from the reaction of ozone, O 3, with zinc dimethyl, Zn(CH 3) 2, and zinc diethyl, Zn(C 2H 5) 2, in a flow system at about one torr pressure reveal a number of interesting electronically-excited species. The Zn(CH 3) 2 + O 3 flame has a pale blue appearance, characteristic of the “cool flame” bands of CH 2O, while the Zn(C 2H 5) 2 + O 3 flame has a deep blue appearance caused by ZnH ∗ emission. In addition the reaction of O 3 with H atoms resulting probably from the decomposition of C 2H 5 radicals in the latter reaction leads to strong OH † ( 2π i) emission (Meinel bands). Also, OH ∗ ( 2Σ +) emission is observed and is found to have a quadratic dependence on OH †. Mechanisms involving the different chemistry of CH 3 and C 2H 5 radicals in the flame are proposed to account for these observations.