Fatty acids are important preliminary materials in biochemical industrial process. Alkaline hydrolysis process is known to be the easiest and fastest way to achieve maximum fatty acids yield. In this study, impact of microwave irradiation assistance on structural characterisation of fatty acids produced from Jatropha curcas oil using alkaline hydrolysis applied in production of fatty acids was verified using nuclear magnetic resonance (NMR) analysis and compared with standard oleic acids. Other physical properties such as free fatty acid, viscosity, density, cloud point and flash point were studied. 1H-NMR and 13C-NMR spectra showed similar structure for both synthesised fatty acids and standard oleic acids with a significant difference in carbon and proton length. The physical properties are also in good agreement for both fatty acids. These findings emphasise that alkaline hydrolysis process under the assistance of microwave irradiation did not change the properties of fatty acids but enhanced the fatty acids production to about 97 wt with shorter reaction time of 15 min. © Penerbit Universiti Sains Malaysia, 2017.