Density, kinematic viscosity, surface tension, and speed of sound of hexyl, octyl, and decyl trimethylammonium bromide aqueous solutions have been determined. The influence of each surfactant concentration upon these physical properties has also been studied at 298 K. The experimental values of these physical properties have been employed to determine the critical micellar concentration for each surfactant as well as to analyze the effect of chain length upon this characteristic parameter.