O2(1Δ)is generated in a bubble column reactor by the reaction between chlorine diluted in inert gas and a basic hydrogen peroxide solution. It is fed to an oxygen-iodine laser system designed to operate under supersonic conditions. The O2(1Δ) yield is measured as a function of the time elapsed from the onset of bubbling, type of diluent, and molar flow rate of chlorine and diluent. The yield when the chlorine is diluted with helium is significantly higher than when diluted with argon. This is explained as a consequence of the shorter residence time of the mixtures with helium where the molecular weight is smaller. A model that accounts for realistic physical and chemical processes in this system is presented. The model is divided into two stages which together describe the processes that occur between the reactor inlet and the measuring point of the O2(1Δ) (before the supersonic nozzles). The first stage describes the processes occurring in the solution. It employs the film model for a fast reaction regime to describe the chlorine absorption, rather than film models where the instantaneous reaction regime is assumed and models assuming instantaneous absorption at the sparger outlet. The second stage describes the processes occurring in the gas phase above the solution. A good agreement between the model predictions and O2(1Δ) yield data from this and other studies is obtained. In particular, the model accounts for the optimal clear liquid height in the reactor. Since the process of chlorine absorption and O2(1Δ) production in the film is common to other types of reactor, the model can be used as a basis for analyzing the performance of those reactors as well.