SUMMARYThe aim was to determine whether the addition of F to an acid soil reduces the concentration of free Al3+and other forms that have been shown to be toxic to plants. The ability of two different extracts to reflect Al speciation in the soil solution was also investigated. Addition of F (0‐5.2μmolg−1) to an acid soil (pH 4.15, soil solution) increased the pH and total concentrations of Al and F in the soil solution whereas Al3+remained constant or decreased. Soil solution pH, total soluble Al and Al extracted by 0.01mCaCl2are not good predictors of the likelihood of aluminium toxicity in soils containing soluble fluo