Abstract: Based on the X ray crystallographic data of Tc complexes for brain imaging agents, geometry optimizations in vacuo of TcO BAT, TcO MAMA, TcO L,L ECD, TcN BAT and TcN L,L ECD complexes are performed with Hartree Fock method and LANL 2 DZ basis set of G98W program. Then solvation free energy for each Tc complex mentioned above in water is calculated by polarizable continuum method (PCM) including models of CPCM and IEFPCM. The results show that solvation free energy of Tc complex is not only an indicator of lipophilicity but also one of the important factors that influence the brain uptake.