Soluble and unsymmetrically cyclized poly(dipropargyl ether) derivatives bearing alpha-substituents were synthesized and characterized. The monomers were propargyl alpha-substituted (methyl, pentyl, methyl phenyl, cyclohexyl) propargyl ethers. Polymerizations were carried out with transition metal catalysts. It was found that MoCl5-based catalysts were very effective for the cyclopolymerization of ex-substituted dipropargyl ethers. The solubility of poly(dipropargyl ether)s was remarkably improved by incorporation of alpha-substituent groups. The resulting polymers exhibited good solubility in common organic solvents such as tetrahydrofuran, chloroform, DMF. The structure of the products was confirmed by IR, UV-visible, and H-1- and C-13-NMR spectroscopy. All of the polymers were amorphous, reddish solids and their weight average molecular weights were in the range of 24.3 x 10(3)-73 x 10(3). The oxidative stability was dependent on the alpha-substituent groups of the poly(dipropargyl ether)s. The electrical conductivities of iodine-doped poly(dipropargyl ether) derivatives were 10(-4)-10(-2) s/cm.