A set of Ni0.45Co0.45Sr0.1LaxFe2-xO4 samples, with varying values of x (0, 0.02, 0.04, 0.06, 0.08, and 0.1), were synthesized using the flash auto-combustion method. The presence of the substituted La3+ ion in the system was verified via various characterization techniques, such as Scanning Electron Microscopy (SEM), Energy Dispersive X-ray (EDX) analysis, Dielectric Analysis, and Electrical Analysis. The morphology of all samples was examined utilizing field emission scanning electron microscopy (FE-SEM). The grain size measured from SEM increased by increasing lanthanum content up to the sample of lanthanum content x= 0.04, then decreased above this value. EDS spectra confirmed Co Ni Sr Fe for x=0 and indicate the presence of these elements beside lanthanum ion in the other samples, without the presence of contamination. At room temperature, the dielectric constant was studied for all samples ranging from 10-2 to 108 Hz. At high frequency, the hopping rate increase and the ferrite material become more conductive, causing a rapid decrease of ε′ and ε″. At lower frequencies, the inclusion of higher amounts of lanthanum leads to a reduction in the values of both ε′ and ε″. The rise in Lanthanum content is associated with a drop in electric conductivity, which can be attributed to the rule governing the increase in grain resistance, resulting in a decrease in AC conductivity. Thermal conductivity and thermal diffusivity increase with temperature. Due to its characteristics, this material may be ideal for thermoelectric and thermomagnetic sensors and switches.