The reaction between the OH radical and HNO₃ represents an important route for the release of NO_x (NO and NO₂) from HNO₃, the most important NO_x reservoir in many parts of the atmosphere. In our laboratory study, we have generated an extensive, high-quality set of rate coefficients for this reaction at different temperatures and pressures and used these to derive a new parameterisation of the rate coefficient for atmospheric modelling.