A series of novel bi-SO3H-functionalized ionic liquids were synthesized and acted as catalysts for the synthesis of beta-acetamido ketones. Compared with traditional single-SO3H-functionalized ionic liquids, less amount of catalysts, higher yields and shorter reaction time are the key features of this methodology. Hammett function values and the minimum-energy geometries of bi-SO3H-functionalized ILs were calculated and the results revealed that the acidities and catalytic activities of ILs in synthesis of beta-acetamido ketones were influenced by their structures. The IL[(PS)(2)pi][OTf](2) with the shortest H-O bond distance had the strongest acidity and the highest catalytic activity. (c) 2012 Elsevier B.V. All rights reserved.