In the exploration of new osmium based double perovskites, Sr2FeOsO6 is a new insertion in the existing family. The polycrystalline compound has been prepared by solid state synthesis from the respective binary oxides Powder X-ray diffraction (PXRD) analysis shows the structure is pseudocubic at room temperature, whereas low temperature synchrotron data refinements reveal the structure to be tetragonal, space group I4/m. Heat capacity and magnetic measurements of Sr2FeOsO6 indicated the presence of two magnetic phase transitions at T-1 = 140 K and T-2 = 67 K. Band structure calculations showed the compound as a narrow energy gap semiconductor, which supports the experimental results obtained from the resistivity measurements The present study documents significant structural and electronic effects of substituting Fe3+ for Cr3+ ion in Sr2CrOsO6.