Riazi and Daubert＇s (Riazi, M.R.; Daubert, T.E. Hydrocarbon Process. 1980, 69, 115) correlations for predicting critical properties and molecular weights have been revised with an extended database. The normal boiling points of the systems investigated range up to 418 degrees C, and the specific gravities range up to 1.175. The results show reasonable improvement over previous correlations.