Hydroxyl ionic liquid (HIL) has been explored as a novel support for Baylis–Hillman catalyst. The HIL-supported catalyst showed a better catalytic activity compared to other IL- immobilized catalyst that has no hydroxyl group attached to the IL scaffold. The hydroxyl group linked on IL played an important role in facilitating efficient catalysis under solvent- free conditions. The corresponding Baylis–Hillman and aza-Baylis–Hillman adducts were ...