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A porous biochar was manufactured through the valorization of waste pork bones, following a three-step process including pre-charring under mild conditions, acid treatment and thermal activation. The influence of the acid (H₂SO₄ and H₃PO₄) and the impregnation ratio on the physicochemical properties of the material was investigated. Acid treatment at 0.2 mmol_acid/g_precursor increased BET area by about 80%, compared to untreated bone char. When using H₂SO₄, higher impregnation ratios significantly enhanced microporosity (up to 263%). This increased microporosity should be associated to a specific reaction mechanism of H₂SO₄ with a source of carbon. On the contrary, the higher activity of H₃PO₄ led to a dramatic removal of porosity for large impregnation ratios (about 20 mmol/g). The acid activation mechanism involves the formation of cation-deficient HAp, which is thereafter decomposed upon …