The use of ionic liquids in catalysis is attracting ever more attention in chemical engineering. In line with this research we have studied Supported Ionic Liquid Catalysts (SILCAs) which consist of immobilized catalytic species, e.g. transition metal particles residing in an ionic liquid layer immobilized on a solid support. We found out that dissolution of Lewis or Brønsted acids into the ionic liquid layer of SILCA has major effects to the activity as well as the product distribution of the catalyst in citral transformation reactions. In fact, one-pot synthesis of menthols from citral was accomplished. The effects of different amounts of added Lewis and/or Brønsted acids to SILCA (one of them or both) were studied in this work.