Several plasticizer esters were synthesized by using acid-functionalized ionic liquids as catalyst. The results indicated that HSO3-functionalized Bronsted acidic ionic liquids show better catalytic and reusable performance than non-functionalized ionic liquids. For each plasticizer ester examined, one or two ionic liquids with high catalytic activity were chosen. Especially, the ionic liquids could be separated easily from the products and be reused at least six times with the conversion of the acid not less than 95%. Therefore, an environmental friendly approach for the synthesis of plasticizer ester is provided. (C) 2007 Elsevier B.V. All rights reserved.