A novel process is described for producing esters of linear monocarboxylic acids containing 6 to 26 carbon atoms, by reacting vegetable or animal oils, neutral or otherwise, with monoalcohols containing 1 to 18 carbon atoms in the presence of a catalyst selected from: mixtures of titanium oxide and alumina having formula:
(TiOx)y(Al2O3)1-y
where x has the value 1.5 to 2.2 and y, representing the weight ratio of the two oxides, has a value of 0.005 to 0.995; mixtures of zirconium oxide and alumina having formula:
(ZrOx)y(Al2O3)1-y
where x has the value 1.5 to 2.2 and y has a value of 0.005 to 0.995; and mixtures of antimony oxide and alumina having formula:
(SbOx)y(Al2O3)1-y
where x has the value 1.2 to 2.6 and y has a value of 0.005 to 0.995, in order to directly produce, in one or more steps, an ester for use as a fuel and a pure glycerin.