Abstract <p>Double perovskite nanoparticles of La₂FeMnO₆ and La₂NiMnO₆ were effectively prepared using combustion synthesis method. X-Ray Diffraction (XRD) and Selected Area Electron Diffraction (SAED) studies verified the formation of the double perovskite phase, with well-defined 2θ peaks corresponding to the respective crystallographic (hkl) planes. The crystallite size was estimated to be in the range of 19–25 nm. High-Resolution Transmission Electron Microscopy (HR-TEM) images revealed a predominantly spherical morphology with uniform particle distribution. Energy Dispersive X-Ray (EDX) spectra confirmed the elemental composition, confirming the presence of La, Fe, Mn, O in La₂FeMnO₆ and La, Ni, Mn, O in La₂NiMnO₆ nanoparticles. The optical band gaps were estimated to be 1.70 and 1.72 eV for La₂FeMnO₆ and La₂NiMnO₆, respectively. Fourier Transform Infrared Spectroscopy (FTIR) spectra showed characteristic vibrational bands at 425, 588, 870, and 1029 cm^–1, corresponding to La³⁺–O^2–, Fe³⁺–O^2–, Mn³⁺–O^2–, and Ni³⁺–O^2– bonding vibrations. Magnetic hysteresis measurements indicated that La₂FeMnO₆ exhibits weak diamagnetic behavior, while La₂NiMnO₆ shows paramagnetic characteristics.</p>