Samarium-based double layered (DL) manganite Sm1.2Sr1.8Mn2O7 was synthesized by sol-gel method and its lattice structure determination was done using powder X-ray diffraction. The sample shows a single-phase body-centered tetragonal structure. The electrical resistivity measurements, both in the absence and presence of the applied magnetic field, were undertaken in the temperature range 70 K – 300 K. The sample is found to exhibit very high electrical resistivity with no insulator-to-metal transition temperature (TIM) in the region of investigation. The analysis of temperature-dependent resistivity data reveals that the conduction in the entire temperature range is well-described by the Efros-Shkloskii (ES) type of variable range hopping (VRH) model which indicates the dominance of electron-electron interactions in the conduction process. The sample shows magnetoresistance of 24% at 74 K with an applied magnetic field of 3 T.