The effect of pressure on the volume of liquid 2-methyl-2-propanamine and six of its mixtures with water has been measured with a bellows volumometer at 278.15, 288.15, 298.14, and 313.14 K. These data have been represented by equations which enable interpolation and extrapolation of the volumetric properties. Isothermal compressibilities evaluated from one of the equations are given. Densities have been evaluated at 0.1 MPa for the pure amine at those temperatures and at 298.14 and 313.14 K for 17 and 9 mixtures, respectively. The effect of pressure on the excess molar volume is illustrated at 298.14 K.