The knowledge of solubility behavior of SO2 + CO2 mixtures in brines at elevated pressures and temperatures is important both in the viability investigations of geologic cosequestrations into deep saline aquifers and in the simulations for flue gas sequestration. We present a model describing SO2 and CO2 as species that do not self-associate but cross associate with water. Two equations of state, PCSAFT/PMSA and eCPA, are applied to work with the model at conditions relevant to geologic sequestration of flue gases: up to 393 K and 450 bar (equivalent to a depth of 4 km) and high salt molality of 6. PC-SAFT/PMSA, which performs better in the whole range of interest, shows that the presence of SO2 makes CO2 less soluble in low-salinity brines (molality <1) but more soluble in high-salinity brines in a temperature range between the critical temperatures of the gases (31.1-157.5 degrees C).