Al-SBA-15 with high surface area and avg. pore diameter was prepared using hydrothermal synthesis. Platinum (0-1.75 wt.%) was incorporated in the Al-SBA-15 support and the catalytic activity was tested using hydrotreated light gas oil (HLGO) as the feed. All the catalysts were thoroughly characterized using N-2 adsorption, ICP, TPD, SAX, FTIR, NMR and TEM analysis. Most of the Al in the support was in the framework with tetrahedral coordination (Al-27 NMR) and the prevalence of the hexagonal mesoporous structure with Pt doping was confirmed from the low angle SAX, BET and TEM study. The incorporation of Al in the framework and the corresponding acidity improvement were confirmed from the TPD and Pyridine FTIR (Py-FTIR) analysis. The dispersion of the Pt was improved until 1.5% Pt incorporation, beyond which the Pt clusters were formed. Screening of the catalysts was carried out in a Parr autoclave and observed that 1.5% Pt/Al-SBA-15 is an effective catalyst for improvement in cetane index of HLGO. These activity results are in correlation with the dispersion of the Pt on Al-SBA-15. More than 90% of aromatic conversions were observed on 1.5% Pt/Al-SBA-15. A maximum cetane index of 64 was observed on 1.5% Pt/Al-SBA-15 at 350 degrees C, whereas reference (Pt/HY) catalyst could not improve the cetane index mainly due to the formation of secondary cracking products. (C) 2012 Elsevier B. V. All rights reserved.