The metal precursor derived from the reaction of Co(II) acetate with the mixed ligands of lysine(Lys) and glutamine(Glu) was used to synthesize Co3O4 nanoparticles. The precursor was characterized by (C, H, N, M), IR, electronic spectra, TGA and effective magnetic moments. Co3O4 nanoparticles were prepared from calcinations of the synthesized precursor at 800 oC. The obtained nanoparticles were characterized by X-ray powder diffraction and transmittance electron microscope. The average particle size is 50 nm. Co3O4 nanoparticles. Adsorption of Methylene Blue on the surface of the Co3O4 was studied. The synthesized metal oxide has 27.2 (mg/g) adsorption capacity of methylene blue (MB) from aquoues solution and removed 95 % of it. This method can be used to remove dyes from wastewater. Langmuir isotherm was the best model represent the adsorption of MB. Pseudo-second-order model with determination coefficient (R2) close to the unity was the best model for adsorption kinetic of MB.