The palladium-catalyzed coupling reaction between an aryl halide and a terminal alkyne, the so-called Sonogashira coupling reaction, was found to occur in water under copper-free conditions using an amphiphilic polystyrene–poly(ethylene glycol) (PS-PEG) resin-supported palladium–terpyridine complex, giving the corresponding aryl-substituted alkyne in high yield. The PS-PEG resin-supported palladium–terpyridine catalyst was recovered simply by filtering the product mixture under air and could be reused three times with only slightly decreased catalytic activity after each use.