The effects of cation and/or anion of two groups of ionic liquids ([EMI]X and [PMI]X, where EMI = 1-ethyl-3-methylimidazolium; PMI = 1-propyl-3-methylimidazolium; X = Cl, Br, and I) on the ionothermal reactions between Cd(NO 3) 2.4H 2O and 1,3,5-benzenetricarboxylic acid (H 3BTC) were studied. Three different Cd-BTC metal-organic frameworks, [EMI][Cd2(BTC)Cl2](1), [EMI][Cd(BTC)](2), and [PMI][Cd(BTC)](3), were formed into crystalline phases. 1 was obtained from reactions in [EMI]Cl, while the same reactions with Cl replaced by Br or I produced a known compound 2. The replacement of EMI(+) by PMI(+) produced 3, irrespective of the nature of X.