We propose a modified phenomenological model for soot formation that occurs during the combustion process of diesel-biodiesel blends. The diesel-biodiesel blend is represented by three generic fuel groups: aromatic, aliphatic, and ester fuels, such that the aromatic content of the diesel fuel and the oxygen content of the biodiesel fuel are considered quantitatively. The soot formation is evaluated for specific selected blends. The different oxidative reactivity between soot particles originating from diesel and biodiesel is accounted for via their oxidation rates. The use of the present phenomenological soot model is demonstrated by its implementation in a computational fluid dynamics (CFD) commercial code for the case of the standard smoke point lamp. Very good agreement was achieved between model predictions and experimental results in terms of maximal soot volume fraction (SVF) and its decrease when switching from plain diesel to a diesel-biodiesel blend. (C) 2017 Elsevier Ltd. All rights reserved.