In the present paper, we confirmed that alkaline phosphatase (ALP) is the main phosphatase present in ascocarps of the edible mycorrhizal fungus Terfezia claveryi. The enzyme was partially purified by precipitation with polyethylene glycol. The purification achieved from a crude extract was fivefold, with 53% of the activity recovered, and acid phosphatase, most of the lipids and phenolic compounds were eliminated. Alkaline phosphatase was kinetically characterised at pH 10.0, the optimum for this enzyme, using p‐nitrophenyl phosphate as substrate. The V_max and K_m values were 0.3 μmol·min⁻¹·mg⁻¹ protein and 9.0 mm, respectively. Orthovanadate was a competitive inhibitor of ALP, with a K_i of 42.5 μm. The enzyme was histochemically localised in the peridium, the hypothecium and in the ascogenic hyphae of the gleba using both colour and fluorescent reactions. The results presented suggest that the ascocarp of T. claveryi, at some stages of its development, may become nutritionally autonomous and independent of the host plant.