Diesel oil-like hydrocarbon production from vegetable oil (sunflower oil) was addressed in a single process using a catalytic fixed-bed pressure reactor, operating in batch wise under subcritical water conditions without external hydrogen supplied. The process has been decoupled identifying the sequential steps involved in the whole reaction. The non-catalytic hydrolysis of triglycerides to form fatty acids (FFA) and glycerol, the aqueous phase reforming of glycerol and the in situ hydrogenation and deoxygenation of the unsaturated fatty acids are the reactions involved to form diesel oil-like hydrocarbons. Under subcritical water condition, the Pt-Ni/Al2O3 catalyst promotes the glycerol reforming, the complete hydrogenation and the partial deoxygenation of the FFA. The combination of Pt-Ni/Al2O3 and Pd/C catalysts as a double fixed-bed allowed a further decarboxylation of FFA to form a C-17-paraffinic hydrocarbon: cetane number of 48.8, density of 0.774 g.cm(-3) and higher heating value of 47.53 MJ.kg(-1); comparable to commercial hydrotreated vegetable oil (HVO). (C) 2016 Elsevier B.V. All rights reserved.