Abstract A multi-component reaction of aldehyde, malononitrile, and 5-amino-3-methyl-1- phenylpyrazole was carried out smoothly in [bmim][BF 4] without any added catalyst. Through this reaction, pyrazolo [3, 4-b] pyridines or substituted malononitrile derivatives were obtained conveniently and controllably at different temperatures. The ionic liquid used can be easily recovered and efficiently reused for at least five runs.