This study aims to gain a quantitative understanding of feedstock effects on hydrodesulfurization (HDS) of middle distillates by developing an overall property-reactivity correlation. The data space consists of HDS reactivities of 13 high-sulfur (0.95-3.17 wt.%) feeds, each characterized by 24 physicochemical properties. Insights gained from a chemometric analysis of the database reveal that the dominant features of the system can be projected onto a three-dimensional subspace spanned by the following properties in order of decreasing importance: degree of feed saturation much greater than sulfur steric hindrance > organonitrogen poisoning. This leads to a correlation for distillate HDS reactivity in terms of the API gravity, and DBTs (dibenzothiophene + sterically hindered dibenzothiophenes), and organonitrogen content (N). Specifically, the correlation gives a scaling "law" of the form: HDS reactivity proportional to (API)(2.18)(DBTs)(-0.31)(N)(-0.2). This correlation is compared and contrasted with two literature correlations. (C) 2003 Elsevier Science B.V. All rights reserved.