Three new complexes of Co(II), Ni(II), and Zn(II), containing ligand of Schiff base (DHMA) derived from methyldopa (mdop) with 3-hydroxybenzaldehyde have been prepared. The synthesized ligand and its complexes were diagnostics by using different physical techniques, The results showed that the complexes have an octahedral shape. In addition it has been studied the adsorption behavior, Uv-Vis technique that applied to survery the isotherm of adsorption. The results showed the possibility of applying the langmair equation. The effect of temperature on the adsorption of Co-complex on the surface of Iraqi Attapulgite clay was studied. The thermodynamic functions ΔGο, ΔHο and ΔSο of Co- complex have been studied and she was ΔGο =(-10.7766, -11.5205, -12.3537)KJ/ mol, this is evidence that the adsorption process is a spontaneous while ΔSο=( 63.6461)J/ mole.K which means an increase in the randomness. The value of ΔHο was (8544.29)J/mole indicate the endothermic natural of the process.