In the following paper, empirical constants are determined by a plasma-chemical model and experimental data of the wetting contact angle. The constants characterize the alteration of the contact angle as a function of the time of the polymer treatment and the kind of the plasma-creating gas. The presented equations of the model connect the contact angle with the empirical constants for arbitrary time intervals of treatment and arbitrary percentage content of the researched gas mixtures and gasses. The chemical rate constants, which describe the process of the plasma modification of the polymer material, are determined. (c) 2006 Elsevier B.V. All rights reserved.