In this paper, we report the absolute measurements of CO2 solubility in aqueous tetra-n-butylammonium bromide (TBAB) solution. The measurement range was 0.2 MPa < P < 4 MPa, 286.15 K < T < 298.15 K, with 0 (pure water) < w(TBAB) < 0.4, where P, T, and wTBAB denote the pressure, temperature, and mass fraction of TBAB in the aqueous feed solutions, respectively. These thermodynamic conditions are outside the hydrate formation region. We evaluated salting-in and -out effects based on the experimental data, and confirmed that the CO2 salting-out effect of TBAB clearly appeared at T = 292 K with w(TBAB) < 0.32 and the salting-in effect may exist for P > 3 MPa and T > 292 K with w(TBAB) >= 0.4 mass fraction of TBAB. (C) 2015 Elsevier Ltd. All rights reserved.