Oxidised oil has been emerged as a root for many chronic diseases. The study was aimed to evaluate the effects of heating on oxidative stability and physicochemical properties of palm olein. Palm olein was heated to 80°C (P80) and 120°C (P120) up to 12 hr. The positional distribution of fatty acids, fatty acid composition (FAC) and iodine value (IV) were analysed using proton-Nuclear Magnetic Resonance (1H-NMR) and carbon- Nuclear Magnetic Resonance (13C-NMR). The slip melting point (SMP), peroxide value (PV), cloud point (CP) and free fatty acid (FFA) contents of the oil were determined according to MPOB Test Methods. Results implied that the regiospecificity of fatty acids in palm olein, FAC, IV and SMP remained unchanged (p>0.05) after both heating treatments for 12 hr. The FFA of P80 and P120 were gradually increased, even so, their FFA were within the acceptance level under prolonged heating for ≤ 10 hr. The CP of P80 and P120 were gradually increased due to an increase in the amount of FFA in the oils. In general, palm olein exhibited good oxidative stability after being heated for up to 2 hr at 80°C and 120°C beyond which the oil deteriorated. Overall, this study revealed that palm olein – as a cooking oil – was thermally and oxidatively stable under normal cooking environment.