The polycrystalline double perovskites La2-xAxFeMnO6 (A = Ca, Sr, Ba; x = 0.0, 0.4) were synthesized through citrate sol-gel auto-combustion technique. The structural, optical, and electrical properties were studied by x-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy at room temperature, while electrical and dielectric measurements were evaluated at temperature ranges from 303 to 423 K. The XRD analysis through Rietveld refinement suggests the single phase orthorhombic (Pnma) symmetry for all the synthesized samples. The infrared reflectivity (IR) spectra were obtained from Fourier Transform Infrared spectroscopy (FTIR) measurements. The spectra were fitted by Lorentz oscillator model, to observe the optical phonon modes. The activation energies were calculated by DC resistivity measurements. According to the resistivity measurement the samples shows the semiconducting nature. The temperature dependent dielectric constant and tangent-loss with varying frequency are measured and discussed.