γ-Al2O3 nanoparticles have been synthesized by electrochemical method using a rectangular aluminum plate as the anode and aluminum plate as the cathode (counter electrode); both electrodes have the same shape and dimensions. TEM, and XRD have been used to characterize the nanoparticles. The results indicated that the size range of γ-Al2O3 nanoparticles was (14- 19) nanometers. Dealt with the studying of the effectiveness of the synthesized nanoparticles on the adsorption of cadmium ion from its aqueous solutions under different temperatures (10, 20, 30, 40, 50) ◦C, Also thermodynamic parameters (ΔS, ΔH, ΔG) were calculated. The equilibrium geometries of γ-Al2O3 nanoparticles have been studied by Density function theory (DFT) using Gaussian 09 package program. The calculated highest-occupied molecular orbital energy (EHOMO) is to be (-.04798 a.u) and the lowest-unoccupied molecular orbital energy (ELUMO) is to be (0.05909 a.u). The calculated activation energy breakage γ-Al2O3-Cd was (35.529 kcal/mole).