A series of hydroxyl-functionalized basic ionic liquids were synthesized and used as catalysts and reaction medium for direct synthesis of dimethyl carbonate (DMC) from methanol and carbon dioxide. The hydroxyl-functionalized basic ionic liquid, namely choline hydroxide (CH) is an effective catalyst with high selectivity (95.2%) to DMC under mild conditions as compared with other similar ionic liquids. The ionic liquid can be reused three times without a significant change in its catalytic activity. Furthermore, the relationship between the catalytic reactivity and OH-functional group was discussed and the mechanism of this synthetic reaction was proposed according to the experimental results and previously reported literatures. (C) 2013 Elsevier B.V. All rights reserved.