Salicylidene-alpha-valine (KHL) and its complexes with Co(II) and Ni(II) of molecular formulae [CoL(H2O).Cl] and [NiLCl], where H(2)L is C6H4(OH)CH=N-CH(COOH)CH(CH3)(2) and M is Co(II) or Ni(II), were prepared, isolated and characterized by elemental analysis, IR spectroscopy, electronic spectroscopy (UV and visible) and magnetic measurements, and their thermochemical behaviour was studied by thermogravimetry (TG) and differential thermal analysis (DTA). The kinetic and thermodynamic parameters n, Delta E(a), Delta H-Theta, Delta G(Theta) and Delta S-Theta, which are the order of the decomposition reaction, the activation energy, and the enthalpy, free energy and entropy change, respectively, were calculated using the TG and DTA curves.