Initially converting the glyceride-based oils derived from biomass into straight-chain alkanes are necessary for producing hydro-processed renewable jet (HRJ). In this study, palm oil was turned into C-15-C-18 alkanes over two different catalysts, Pd/C and NiMo/gamma-Al2O3, with various reaction conditions such as temperature, pressure, weight hourly space velocity (WHSV) and H-2-to-oil ratio. The fresh and used catalysts after hydro-processing reaction were then characterized through the techniques including TGA, FTIR, XRD and SEM. The liquid products were analysed through GC-MS/FID and the concentrations of C-15-C-18 were determined. The gas products, such as CO2, CO, C3H8, CH4 and H-2, were analysed through GC-TCD for indirectly "visualizing" the reaction, including the performances of hydro-deoxygenation (HDO) as well as decarbonylation/decarboxylation, hydrogenolysis, the occurrence of methanation and the consumption of hydrogen. The suggested experimental conditions over these two catalysts were elaborated based on the concentration of n-alkanes and gas products. (C) 2019 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.