The pi-allylnickel-catalyzed living coordination polymerization of methylallene gave polymers with predictable molecular weight and narrow molecular weight distribution in high yields. The polymers possessing various microstructural units (i.e., the ratio of the 1,2- and the 2,3-polymerizations), produced by varying the nature of the catalyst and the solvents, were subjected to the hydroboration with borane reagents such as borane tetrahydrofuran complex (BH(3)center dot THF) and 9-borabicyclo[3.3.1]nonane (9-BBN). Subsequent oxidation gave poly(alcohol)s whose hydroxy-content could be varied by the borane reagents used. For example, the quantitative conversion of the double bonds in poly(methylallene) into the hydroxy group was attained by the hydroboration using an excess amount of BH(3)center dot THF. Thermal properties of poly(alcohol)s were found to be dependent upon the microstructure and the hydroxy-content of the polymers.