Pressure dependence of radical densities in various gas discharges is investigated using a simple plasma kinetics model. Modifications and corrections were made to the previous formulation of the model. For this purpose the dissociation degree of feed gas was addressed in terms of the pressure, and empirical expressions for the dissociation degree were suggested for further analysis. Some speculations on the lifetime of the radicals in the discharge for mixed gas discharges were also made. Experimental data presented in the literature were analyzed based on this modified and corrected model. The validity of the model for a global application was testified by comparing the expectations of the model with the experimental result published in the literature. © 2004 Elsevier B.V. All rights reserved.