The use of vegetable oils as a fuel in burners is an alternative which offers, certain advantages over the use of vegetable oils in engines. The present work explores the use of four oils: rapeseed, sunflower, soya, and a commercial mixture-seed as heating fuel oil (HFO). The article relates the composition of the fatty acids in the various vegetable oils to the combustion products obtained in an emulsion burner. The work has been carried out in three stages. Firstly, describing the use of vegetable oils as a fuel and determining the fatty add composition by proton NMR. Secondly, combustion of the vegetable oils studied is performed using an emulsion burner, varying the burner adjustments, and analysing combustion gases. Thirdly, exploring the link between the fatty acids contained in each oil and the combustion efficiency and combustion gas concentration for each oil type. Due to the fatty acids they contain, not all the oils behave equally, even though their description as fuels is very similar. (C) 2014 Elsevier B.V. All rights reserved.