The interaction of mineral dust with N<sub>2</sub>O<sub>5</sub> was investigated using both airborne mineral aerosol (using an aerosol flow reactor with variable relative humidity) and bulk samples (using a Knudsen reactor at zero humidity). Both authentic (Saharan, SDCV) and synthetic dust samples (Arizona test dust, ATD and calcite, CaCO<sub>3</sub>) were used to derive reactive uptake coefficients (γ). The aerosol experiments (Saharan dust only) indicated efficient uptake, with e.g. a value of γ(SDCV)=(1.3±0.2)×10<sup>−2</sup> obtained at zero relative humidity. The values of γ obtained for bulk substrates in the Knudsen reactor studies are upper limits due to assumptions of available surface area, but were in reasonable agreement with the AFT measurements, with: γ(SDCV)=(3.7±1.2)×10<sup>−2</sup>, γ(ATD)=(2.2±0.8)×10<sup>−2</sup> and γ(CaCO<sub>3</sub>=(5±2)×10<sup>−2</sup>. The errors quoted are statistical only. The results are compared to literature values and assessed in terms of their impact on atmospheric N<sub>2</sub>O<sub>5</sub>.