The reaction between sulfurous acid (H2SO3) and lithium hydroxide (LiOH) produces lithium sulfite (Li2SO3) and water (H2O). The chemical equation for this reaction is:

H2SO3 + 2LiOH → Li2SO3 + 2H2O

In this reaction, sulfurous acid donates a hydrogen ion (H+) to lithium hydroxide, forming water. The sulfite ion (SO3^2-) from the sulfurous acid then combines with the lithium ions (Li+) from the lithium hydroxide to form lithium sulfite.

Lithium sulfite is a white, water-soluble salt that is commonly used as a food preservative and antioxidant. It is also used in the production of paper, textiles, and glass.