In biogeochemistry, remineralisation (UK spelling; US remineralization) refers to the transformation of organic molecules to inorganic forms, typically mediated by biological activity.

Usually remineralisation relates to organic and inorganic molecules involving biologically important elements such as carbon, nitrogen and phosphorus. For example, the following simplified equation shows the complete remineralisation of organic material with a standard Redfield ratio to oxidised inorganic minerals such as carbon dioxide, nitrate (nitric acid) and phosphate (phosphoric acid).

(C₁₀₆H₁₂₄O₃₆) (NH₃)₁₆ (H₃PO₄) + 150 O₂ $\backslash rightarrow$ 106 CO₂ + 16 HNO₃ + H₃PO₄ + 78 H₂O + energy

In reality, such complete remineralisation is likely to involve several stages each involving different organisms and metabolic pathways. For example, in the case of nitrogen, its transformation from ammonia (NH₃) in the equation above, to nitrate involves the process of nitrification, usually mediated by a series of bacteria.