Densities of aqueous solutions of Me4NBr, Et4NBr, and Bu4NBr have been measured using a magnetic float apparatus. The concentration range was from (0.005 to 0.04) mol·kg−1. The temperatures were (278.15, 288.15, 293.15, and 298.15) K. The experimental values were used to calculate apparent molal volumes, partial molal volumes at infinite dilution, and partial molal expansibilities at (278.15, 288.15, 293.15, and 298.15) K. The ionic contributions to the properties were calculated using the additivity rule. The results are interpreted in terms of solute−solvent interactions.