AbstractThe structure of polymers obtained by polymerization of methoxyallene and ethoxyallene with transition‐metal catalysts depends on the catalyst employed. Rapid polymerization at 0°C through the unsubstituted double bond occurred with π‐allylnickel halides, NiCl2/AlEt3and CoCl2/AlEt3, yielding polymers with the structureTypical Ziegler–Natta catalysts (TiCl4, VOCl3or FeCl3with AIEt3) gave polymers mainly with the structurealthough some of the structural units were probably present as well. Polymers having conjugated double bondswere prepared with PdCl2, [(π‐allyl)PdCl]2, and PdCl2(C6H5CN)2as catalysts. Palladium iodide produced polymers with all three of the above structural units present. Polymerization occurred more slowly with these palladium catalysts. A preliminary examination of the effect of variation of solvent, ligand, co‐catalyst, and temperature on the rate and structure of the polymers obtained with the palladium catalysts