The reaction processes in chemical oxygen-iodine laser nozzle flows are investigated analytically. In the transport equations for the reacting species, order-of-magnitude arguments are applied to retain the dominant terms. The effects of local flow properties on the chemical kinetics are found in terms of a transformed coordinate which is a function of the nozzle shape and inlet flow conditions. Approximate closed-form solutions for the iodine dissociation, oxygen yield, and the dissociation cost are derived. The results indicate that the chemical processes occur predominantly in the subsonic section of the nozzle where the pressure is high and velocity is low.