with a lower critical solution temperature (LCST) in water. Pdnanoparticles were immobilized on these poly(NIPAM-co-4-VP) hydrogels. The heterogeneous Pdcatalyst showed high catalytic activities for carbon–carbon couplingreactions, such as Suzuki–Miyaura, Heck–Mizoroki, and Sonogashira couplingreactions in water. The Pdcatalystimmobilized on poly(NIPAM-co-4-VP) hydrogel (NIPAM:4-VP = 1:1 M ratio)