Lithium carbonate, saturated (about 1.3%) is an aqueous solution of lithium carbonate (Li2CO3). This solution contains the maximum amount of dissolved lithium carbonate that is soluble in water at a given temperature.

In histology and histochemistry, a saturated lithium carbonate solution is used as a differentiation solution in the staining technique, for example, in staining with hematoxylin and eosin (H&E). Here, the lithium carbonate solution is used to remove excess hematoxylin dye from the tissue section and thus control the staining process. The result is differential staining of the cell nuclei (blue) and cytoplasm (pink).

Outside histology, lithium carbonate also has applications in industry, particularly in the manufacture of glass, ceramics and lithium-ion batteries. In medicine, it is used as a mood stabilizer in the treatment of bipolar disorder.