In this research, we effectively substituted Mo with Nb in the La6MoO12 compound by incorporating Sm2O3 through the solution combustion method and investigated their structural and electrical properties. Analysis of the X-ray diffraction patterns validated a shift from the rhombohedral R2 phase to the R1 phase as the Nb concentration increased. Rietveld refinement of the X-ray diffraction data yielded comprehensive microstructural insights into the La5.4Sm0.6Mo0.85Nb0.15O12±δ compound (R1 phase). Energy-dispersive X-ray spectroscopy (EDX) and elemental mapping were employed to validate the homogeneous distribution of all elements across the compositions. Impedance spectra exhibited a negative temperature coefficient of resistance (NTCR) behavior in the samples. The La5.4Sm0.6Mo0.94Nb0.06O12±δ composition (in the R2 phase) displayed the highest bulk conductivity value. Analysis of different spectra revealed a scaling behavior indicative of a temperature-independent mechanism. Current-voltage (I-V) measurements confirmed the presence of leakage current attributed to interface-limited Schottky emission, with the La5.4Sm0.6Mo0.85Nb0.15O12±δ composition exhibiting the highest barrier height (0.83 eV).