TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Catalyst: Supported catalyst (I) in which the support is an amorphous mineral selected from alumina, silica, aluminosilicates, magnesia and clays, preferably alumina. (I) also contains dopant element(s) selected from phosphorus, fluorine and boron, preferably phosphorus in amounts of more than 0.5 wt.% and less than 8 wt.% P2O5 based on total (I).    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Method: Conversion by decarboxylation/decarbonylation is limited to at most 4%. The process may be carried out in a fixed bed or a fluidised bed. The effluent from hydrodeoxygenation is subjected to at least one separation stage, preferably gas/liquid separation and separation of water and at least one liquid base hydrocarbon, preferably followed by elimination of nitrogen compounds from the base hydrocarbon; after this, at least part of the hydrocarbon is hydro-isomerised in presence of a hydro-isomerisation catalyst, preferably comprising Group VIII and/or Group VIB metal(s) for hydro-dehydrogenation and amorphous mineral support(s) for hydro-isomerisation (especially an active platinum phase and a hydro-isomerisation function based on ZBM-30). EXAMPLE - Pre-refined colza oil (density 920 kg/m3; sulfur content less than 10 ppm; cetane index 35) was passed at 50 ml/hour through an isothermal reactor packed with 100 ml hydro-treatment catalyst, together with hydrogen at the rate of 700 Nm3 per m3 of charge, while the reactor was operated at 300 degrees C and 5 MPa. The catalyst (HDT1) was a MoP/Al2O3 catalyst containing 25.3% MoO3 and 6.1 wt.% P2O5, supported on gamma-alumina; this was evaluated in the sulfide form by increasing the amount of sulfur in the charge to 50 ppm in a prior run using gas oil containing 2 wt.% dimethyl disulfide. This gave a conversion of 100 (100) wt.% to a product in which the ratio of even-numbered hydrocarbons (14-24C) to odd-numbered hydrocarbons (15-23C) was 36.4 (4.6) and the total yield of even- and odd-numbered hydrocarbons was 85 (81) %. Values in brackets were obtained with a nickel-molybdenum-phosphorus (21% MoO3, 5% P2O5, 4.3% NiO) catalyst on the same support, under the same conditions (with pre-sulfurisation as above).