Zeolitic Imidazolate Framework-67 (ZIF-67) materials have successfully been synthesized in aqueous solution at ratios of Co2+, 2-methylimidazole, and triethylamine as a deprotonating agent, i.e. 1:5:5; 1:10:5 and 1:10:10, in the presence and the absence of acetic acid. The XRD patterns of all synthesized materials showed peak characteristics at 2 thetas which were the same as simulated ZIF -67. The results of FTIR analysis showed appearance absorption bands at the same wavenumber for all synthesized materials. The presence of acetic acid, however, resulted in the decrease in intensities of the XRD peaks and altered the surface morphology to become irregular. All materials were examined their performance as an adsorbent for the removal of methyl orange in water. It was found that the highest adsorption capacity of 214 mg/g was shown by ZIF-67(1:10:5AA). Pseudo-second order kinetics and Langmuir isotherms correspond to all synthesized materials.