This study focuses on the thermal and mechanical properties of 1,2-polybutadiene (1,2-PBu) and 3,4-polyisoprene (3,4-PI) with a transition metal salt, bits (acetonitrile)dichloropalladium(Ⅱ) (PdCl2). Upon mixing in tetrahydrofuran (THF), effective coordination crosslinks are formed because the acetonitrile ligands of the palladium salt are displaced by olefinic pendant groups of the polymers. The palladium-catalyzed exothermic chemical reaction in solid films was characterized via differential calorimetric and differential thermal analysis High-temperature infrared experiments up to 200 ℃ identify irreversible chemical crosslinking reaction that occurs in complexes of 1,2-PBu and palladium chloride. If the d⁸ square-planar palladium salt coordinates to olefinic side groups in both 1,2-PBu and 3,4-PI, then transition-metal catalyzed dimerization reaction should induce compatibility. Transition-metal coordination and thermally induced palladium catalyzed dimerization reactions in 1,2-PBu/3,4-PI/PdCl2 ternary blend system provide a new route to compatibilize industrially important diene-based polymers.