The vapour pressure of pyridine N-oxide was measured using a boiling point method at different temperatures from 389.02 to 546.33?K and the constants of the Antoine equation for the substance were determined. The vapourisation enthalpy of pyridine N-oxide at the normal boiling point is calculated to be 58.8 +/- 1.8?kJ?mol-1. Based on Othmer's method, the standard enthalpy of vapourisation ${\rm \Delta }_{{\rm vap}} H(298.15\;{\rm K})$ is estimated to be 66.6 +/- 0.1?kJ?mol-1 by using pyridine as the reference substance. Furthermore, Watson equation is employed to verify the reliability of ${\rm \Delta }_{{\rm vap}} H(298.15\,{\rm K})$and the results demonstrate that the value of ${\rm \Delta }_{{\rm vap}} H(298.15\;{\rm K})$ is acceptable. (C) 2011 Canadian Society for Chemical Engineering