A zinc metal-organic framework (MOF), [Zn 4 (BTC) 2 (μ 4 -O)(H 2 O) 2 ], was synthesized with Zn(NO 3 ) 2 ·6H 2 O and H 3 BTC ligand (H 3 BTC=1,3,5-benzenetricarboxylic acid) by ionothermal synthesis in 1-ethyl-3-methylimidazolium bromide ionic liquid as solvent. The compound features a 3-D architecture constructed by linking [Zn 4 (μ 4 -O)] subunits with BTC 3− ligands. They are composed of two five-coordinated and two four-coordinated Zn ions, different from the [Zn 4 (μ 4 -O)] units of other MOFs. The effect of reaction conditions to the MOF structure is discussed.