Abstract <p>The effects of Mg²⁺ on the combustion behavior of Loy Yang lignite (LY) were studied. The combustion behaviors of all samples were investigated using a thermogravimetric (TG) analyzer. Moreover, all samples were characterized using Fourier transform infrared (FT-IR) spectrometer with a DRIFT model, scanning electron microscope (SEM), and a specific surface area and porosity analyzer. The results showed that Mg²⁺ was successfully loaded into the acid-washed sample (LYA) in the form of carboxylates. The addition of Mg²⁺ blocked partial pores of LYA. Compared with that of LYA, the peak temperatures of the Mg²⁺ loaded samples (LYA_Mg0.05 and LYA_Mg0.1) decreased by 2.0 and 2.4%, respectively. The activation energies of LYA_Mg0.1 and LYA_Mg0.05 were lower than that of LYA. Overall, Mg²⁺ could catalyze the combustion of lignite. The higher the loading content, the more obvious the catalytic effect is. Additionally, we proposed a mechanism of Mg²⁺ catalyzing the combustion of lignite, i.e., Mg²⁺ acts as an oxygen carrier, which could enhance the transport of oxygen. Consequently, a catalytic effect of Mg²⁺ on lignite burning was observed.</p>