Apparatus has been devised for automatically measuring and recording vapor pressure (1 to 35 atm) and temperature (−40 to +100°C) of pure liquids or solutions. The measurements are performed on a dynamic system whereinPandTare changed at very slow rates. ManyP‐Tdata sets are recorded in a single run, providing the input for a computer program which correlates the two variables. Data for dichlorodifluoromethane are presented and compared with literature values. It is concluded that precise and accurate results are obtained with the automatic apparatus. Furthermore, the data processing program provides valuable information for analyzing the operation of the equipment.