An interaction model i s presented for the prediction of viscosities a t normal pressures of gas mixtures containing a polar and a nonpolar constituent. This model is based an the princi l e of corresponding states and requires T R , the viscosity component . Sutherland (15), Wilke (19), and Yoon and Thodos (20). The development of these methods has been largely associated with the kinetic theory of nonpolar spherical molecules in their dilute gaseous state. Viscosity measurements available inand Cheung, Bromley, and Wilke ( 3 ) modify their developments for nonpolar gases to ac'count for the nature of the polar constituent in the mixture. The present study attempts to extend the application of the corresponding states theorem as used by Yoon and Thodos (20) for the viscosity of nonpolar gas mixtures to include polar constituents.A comprehensive literature search for the procurement of viscosity data of gas mixtures containing polar components showed that such information was limited to binary mixtures containing one polar and one nonpolar constituent. The only exception includes a ternary system with air as a nonpolar constituent. No experimental data could be found for polar-polar binary g a s mixtures. Consequently, this study i s limited to the analysis and interpretation of viscosity data of available polar-nonpolar binary mixtures. The paucity of viscosity data for polar gas mixtures extends even to polar-nonpolar binary mixtures and limits the polar constituent to be hydrogen chloride, sulfur dioxide, ammonia, and hydrogen sulfide. These four substances are strongly polar a s indicated by their significant dipole moments (12). Substances such as carbon dioxide and nitrous oxide possessing weak dipole moments can be considered essentially nonpolar. Experimental information for polarnonpolar gas mixtures i s reported only by Chakraborti and Gray (2), Iwasaki et al. ( 9 ) , Jung and Schmick ( l o ) , and Trautz and co-workers (16 to 18). For polar-nonpolar gas mixtures, Mason and Monchick (11) TREATMENT OF EXPERIMENTAL DATAThe analysis developed in this study represents an extension of the method outlined by Yoon and Thodos (20) for nonpolar gas mixtures. Their method considers a mixture to be a pure substance and utilizes TL, the pseudocritical temperature of the mixture, to establish T R in order to obtain &Ern, the viscosity modulus for the mixture.