The apparent molar volumes of six symmetrical tetraalkylammonium bromides (Et(4)NBr to Hep(4)NBr) have been determined in acetonitrile at (298.15, 308.15, and 318.15) K from precise density measurements. The apparent molar volumes have been extrapolated to zero concentration to obtain the limiting values at infinite dilution. The infinite dilution partial molar expansibilities have also been calculated from the temperature dependence of the limiting apparent molar volumes.