This study examines the influence of acid activation (HCl) of an Ypresian clay on the synthesis of porous materials and the clarification of soybean oils. The clay was collected from the Palaeocene–Eocene transition between the El Haria and Chouabine formations in the Meknassy–Mezzouna basin, central Tunisia, and was subjected to chemical and mineralogical characterization. The clay consists of smectite, sepiolite and palygorskite, with smectite dominating and accessory quartz and dolomite. The clay has a relatively high specific surface area (50.47 m2 g–1), which increases to 100 m2 g–1 after activation by HCl. The optimal activation conditions were obtained at 75°C for 4 h with 3 N HCl. Acid activation disrupted the smectite structure (causing leaching of structural cations), dissolved dolomite, formed amorphous porous material and caused H for Ca ion exchange in the smectite interlayer. The acid-activated smectitic clay provided encouraging results regarding the clarification of neutral soybean oil after comparison with the Tonsil commercial bleaching earth product. The bleaching capacity of the activated clay was 78.08%, which is higher than that of Tonsil (56.12%). This was corroborated by visual examination of the clarified oils.