TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Components: The heterogeneous catalyst is of formula (M(m)PO(m+5-3x)/2Nx) (I), where m+5-3x is greater than or equal to 0. The metal cation is aluminum or titanium. The catalyst is a nitrogen aluminophosphate compound of formula (AlPO(8-3x2)/2Nx) (III).x2 = 0-2.67.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Components: The fatty substance of animal or vegetable origin is oil of palm concrete or olein, soybean oil, palm kernel oil, coconut oil, babassu oil, old or new rapeseed oil, classic or oleic sunflower oil, corn oil, cotton oil, groundnut oils, Jatropha curcas, castor oil, linen and crambe oil, all oil obtained from sunflower or canola oil by genetic modification or hybridization or from algae or microalgae, cooking oils, varied animal oils such as fish oils, seals, tallow, lard, or fat derived from treatment of wastewater and poultry fat. The aliphatic monohydric alcohol is 1-12C, preferably 1-5C aliphatic monohydric alcohol. Preferred Process: The process is carried out: at a temperature of 130-220 degrees C, at a pressure of below 100 bar and with an excess of mono-alcohol by ratio of fatty substance/alcohol stoichiometry; in a discontinuous manner; continuously in a fixed bed or with autoclaves and decanters in series; and in a fixed bed at a pressure of 1-7 MPa and a space velocity (VVH) of 0.1-3, preferably 0.3-2 in the first step and the weight ratio of alcohol/oil is 3/1 to 0.1/1. The process is carried out in one or two steps by adjusting the degree of conversion for obtaining an ester fuel present in monoglyceride content of at most 0.8 mass%, diglycerides of at most 0.2 mass%, triglycerides of at most 0.2 mass%, glycerin of at least 0.25 mass%, and a glycerin purity of 95-99.9%, and preferably 98-99.9%. EXAMPLE - Rapeseed oil (21 g), ethanol (30 g) and aluminum phosphate oxynitride powder form (0.5 g) were introduced in a closed reactor at room temperature, where the weight ratio of methanol and oil was 1, which corresponds to a molar ratio of 27.5. The reactor was then closed, agitated and heated to 180 degrees C using a heating magnetic stirrer. The temperature of the reaction was stabilized at 180 degrees C after 20 minutes heating. The pressure was autogenous pressure of alcohol at the working temperature. After 6 hours of reaction, stirring was stopped and the reactor was allowed to cool to room temperature. The final effluent was washed with a saturated aqueous sodium chloride to give a composition.