This paper is the second of a series dealing with determinations at the National Physical Laboratory of fixed points on the scale of high pressures. It gives the results of an accurate investigation of the vapour pressure of pure carbon dioxide at the temperature (0.0100°c) of the triple point of water, measured by direct reference to the Laboratory's standard pressure balances. This quantity has been widely used as a reference pressure for the local calibration of pressure balances. The value obtained is 3.485 64 MN m^-2 with an estimated uncertainty of ±0.000 12 MN m^-2. This result is compared with those of several previous investigations and the possible cause of discrepancies are discussed.