Reactive adhesives (also named cross-linkable adhesives) are adhesives that cure by chemical reaction. These adhesives are cross-linked after being applied. They are generally made out of two ingredients: monomer (resin) and initiator. A reaction of polymerization / cross-linking occurs when the two parts are mixed, which solidifies the adhesive. Reactive adhesives can also react with the surface of the substrate they are applied on.

The performance advantage of reactive adhesives over hot melt or solvent borne adhesives is that they cure to a material that resists melting. The resulted adhesive has excellent temperature and environmental resistance, while maintaining high bond strength.