The saturation pressure of 2-methylpropan-2-ol and 2,4,4-trimethyl-1-pentene at (305 to 356) K was measured by the ebulliometric method. The vapor-liquid equilibrium (VLE) (P, T, x, y) was measured by the ebulliometric method for the system benzaldehyde + 1-methylethylbenzene at 373.15 K and for the system 2-methyl-propan-2-ol + 2,4,4-trimethyl-1-pentene at (313.16, 333.14, and 353.18) K. A positive azeotrope was found in the last system. The experimental vapor pressures were correlated with Antoine equation and for 2-methyl-propan-2-ol. VLE was correlated with Redlich-Kister four-parameter equation.