A series of alkoxy group-functionalized UiO-66 were designed for hydrogen chloride adsorption from aqueous solution, which were characterized by various methods to verify the structures and study the adsorption mechanism. A volcano-shaped change of adsorption capacity was discovered. UiO-66-C-2 exhibited the highest adsorption capacity and excellent structure stability. The adsorption kinetics, isotherms, and thermodynamics were studied. It was found that the pseudo-second-order kinetic model fit the experimental data well in kinetic studies. Meanwhile, both Henry and Freundlich models fitted the isotherm experiment data well. The thermodynamics parameters further confirmed that hydrogen chloride adsorption on UiO-66-C-2 was a spontaneous and exothermic physisorption process. Regeneration experiment demonstrated that UiO-66-C-2 has high regeneration efficiency and no significant change in adsorption capacity was confirmed after recycles. All the results substantiated that UiO-66-C-2 could be an efficient solution to treatment of acidic wastewater.