Crystallinities for three samples of crystalline polypropylene powders have been determined by a gas chromatographic method. These results are correlated with a simple equation. Furthermore, Henry's law constants of five nonpolar solutes and four polar solutes in the crystalline polypropylene powders were measured at temperatures from 349.5 to 497.1 K by using a gas chromatographic method. Experimental data above the melting temperature of polypropylene are correlated with a method based on a corresponding states model recently proposed by Zhong ef ah. (1997), The correlation was extrapolated below the melting temperature to get Henry's constants in the amorphous phase. Taking the crystallinity into consideration, the estimated Henry's constants are in good agreement with the experimental data.