Abstract: The model of plasma chemistry was developed to predict the appropriate electron mean energy and flow rate and discharge pressure for the generation of singlet oxygen molecule, based on physical chemistry with a simple reaction model. The model included the collisions of atom with molecule and electron with other species. It was found that electron mean energy must be less than 2.5eV. An optimum electron mean energy can be found at constant discharge pressure and flow rate. Electron density and discharge pressure played the second role among the parameters.