A new unsymmetrical Schiff base ligand (H2LLi) was synthesized using L-lysine, o-vanillin and salicylaladyde. Thorium(IV) complex of this ligand [Th(H2L)(NO3)](NO3)2.3H2O have been prepared and characterized by elemental analyses, IR, UV and molar conductance. The thermal decomposition kinetics
of the complex for the second stage was studied under non-isothermal condition by TG and DTG methods. The kinetic equation
may be expressed as: dα/dt=A.e-E/RT.1/2 (1-α).[-ln(1-α)]-1. The kinetic parameters (E, A), activation entropy ΔS¹and activation free-energy ΔG¹were also calculated.