The binodal curves of 1-butyl-3-methylpyridinium tetrafluoroborate ([3-MBP] [BF4]) + NaH2PO4/Na2SO4 + H2O aqueous two-phase systems (ATPSs) at T = (310.15, 318.15, and 327.15) K were experimentally determined. Three nonlinear equations were fit to the binodal data. Tie-line data were fit to the Othmer-Tobias, Bancroft, two-parameter, and Setschenow-type equations. The results were consistent with the experimental data. The effective excluded volume (EEV) values were determined using the binodal model for these two systems. According to the binodal curves and tie-line data obtained at different temperatures, the effect of temperature on the ATPSs was also discussed.