The present study demonstrates the use of rhodium-based monolithic catalyst for onboard reforming of diesel fuels. Experimental results from hydrogen generation of n-tetradecane, low-sulfur and Fischer-Tropsch diesel, via autothermal reforming (ATR), were acquired with a catalyst consisting of 3 wt% Rh supported on alumina doped with Ce/La. The catalyst was prepared by impregnation using the incipient wetness technique, and deposited onto a 400 cpsi cordierite monolith. Furthermore, the catalyst was tested over ranges of oxygen-to-carbon and water-to-carbon feed ratios, both in a bench-scale and a full-scale reactor. Fresh powder samples of the catalyst were characterized by XRD, N(2)-BET, H(2) chemisorption, H(2)-TPR and XPS analyses. The activity results showed that high fuel conversions and hydrogen production could be achieved with 3 wt% Rh for all fuels. Furthermore, the highest formation of CO and C(2)H(4) was found in the product gas stream from the low-sulfur diesel. In addition, partial oxidation and steam reforming reactions were identified by closely studying the distribution of the analyzed product gas composition and the temperature measurements. The characterization results showed the presence of finely dispersed Rh particles in the support. Furthermore, bulk and surface rhodium oxides were detected, which have been suggested to be one of the major active phases for ATR of diesel. Bulk and surface cerium oxides (CeO(2)) and surface La in the dispersed phase were also found to be present in the catalyst composition. These promoters are believed to improve the catalyst activity and durability. (C) 2010 Elsevier B.V. All rights reserved.