The uptake coefficients (Γ) for OH radicals on some dry salts of tropospheric interest (NaCl and NH<sub>4</sub>NO<sub>3</sub>) have been investigated as a function of temperature using the flow tube technique combined with an EPR spectrometer as a detection method. The temperature dependence of Γ-values measured over the temperature range 245–340 K can be expressed in Arrhenius form: Γ<sup>OH</sup><sub>NaCl</sub>=(1.2±0.7)×10<sup>–5</sup>exp[(1750±200)/T] and Γ<sup>OH</sup><sub>NH4NO3</sub>=(1.4±0.5)×10<sup>–4</sup>exp[(1000±100)/T]. These Arrhenius expressions lead to very similar Γ-values (~4×10<sup>–3</sup>) for both salts studied at 300 K. It is shown that the heterogeneous OH sinks on solids aerosol play a very minor role in tropospheric chemistry in comparison with the homogeneous sinks.