Significance Ionic liquids (ILs) are employed for air-drying for the first time. The experimental gas-liquid equilibrium (EQ) of N-2/O-2+[EMIM][BF4] and N-2/O-2+[EMIM][BF4]+H2O systems under a broad temperature range are measured. The new modified UNIFAC-Lei model is successfully extended to predict the N-2/O-2-IL-H2O system based on extensive phase EQ data. The air-drying experiment using [EMIM][BF4] as an absorbent is conducted, confirming that this new technology is effective and efficient. (c) 2018 American Institute of Chemical Engineers AIChE J, 65: 479-482, 2019