This study investigates the synthesis, characterization, and catalytic activity of functionalized iron oxide nanoparticles for the thermal decomposition of potassium nitrate (KNO3). The iron oxide nanoparticles (Fe3O4 NPs) were synthesized using a co-precipitation method and then functionalized with 11-Bromoundecanoic (Fe3O4@Br) and 11-Aminoundecanoic acids (Fe3O4@NH2) by chemical route. The functionalized nanoparticles were characterized using Transmission electron microscopy (TEM), Thermogravimetric analysis (TGA), Fourier-transform infrared spectroscopy (FT-IR), and vibrating sample magnetometry (VSM). The characterization results revealed that the nanoparticles have a uniform size of approximately 8.3 nm, exhibit superparamagnetic behavior, and are successfully functionalized. To compare short and long-chain ligands, we included our previously reported quaternary (Fe3O4@NR4 +) and tertiary (Fe3O4@NR3) amine-functionalized magnetic catalysts in the catalytic studies. Among the different functionalized nanoparticles, Fe3O4@NR3 exhibited the most pronounced catalytic activity, significantly reducing the decomposition temperature (DT) of KNO3 to 683.2 degrees C compared to the other nanoparticles. This enhanced catalytic activity is attributed to the specific interaction between the Fe3O4@NR3 surface and KNO3 molecules. The activation energies (E a) for the thermal decomposition of KNO3 were calculated using the ASTM e628 method, confirming the decrease in activation energy for the Fe3O4@NH2 + KNO3 mixture compared to pure KNO3. These findings demonstrate the potential of tailored surface functionalization to improve the catalytic performance of Fe3O4 nanoparticles for KNO3 decomposition, which has potential applications in various fields such as propellants, explosives, and pyrotechnics.