The new eight-coordinate complex of thorium(IV) was synthesized by the reaction of Th(NO3)4.4H2O with 1,10-phenanthroline(phen) and 2-hydroxy-5-sulfobenzoic acid (SSA) by coprecipitation method. An environment friendly chelating agent sulfosalicylic acid (SSA) having oxygen donor atoms, phen with delocalized π-electron system, and N-donor atoms were used during the preparation of complex. The complex was characterized on the basis of elemental analysis, Fourier transform infrared (FTIR) spectroscopy, UV–Vis spectroscopy, powder X-ray diffraction (PXRD), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and scanning electron microscopy (SEM). The complex was further assessed for structural and magnetic behavior. The results revealed that the complex has been completely formed as eight coordinated, amorphous in nature, diamagnetic, air stable, granular surface morphology, and water soluble. Furthermore, the FTIR studies of the complex demonstrate coordination of Th(IV) with SSA, phen, and nitrate by the participation of oxygen and nitrogen atoms. According to the results obtained, the changes in the IR spectra indicate that the coordination takes place via nitrogen atoms of phen, oxygen atoms of SSA and nitrate ions, the former two acting as bidentate ligands while as the latter coordinate via the monodentate mode. Moreover, from the emission spectra, the complex also showed emission atom excitation wavelength of 290 nm.