Phosphonium ionic liquids exchanged with bicarbonate and methylcarbonate anions (CILs) exhibit catalytic performances comparable to those of sterically hindered (non nucleophilic) organosuperbases such as DBU. At 25-50 °C, under solventless conditions, CILs efficiently catalyze the Henry addition of different aldehydes and ketones to nitroalkanes: not only they allow the selective formation of nitroaldols but they unlock a novel high-yielding access to dinitromethyl derivatives of ketones.