Novel ketenes, (4-chlorophenyl)ethylketene and (4-bromophenyl)ethylketene, were synthesized by dehydrochlorination of 2-(4-halophenyl)butanoyl chlorides, and their anionic polymerizations by lithium (4-methoxyphenoxide) in tetrahydrofuran at -20 degreesC were carried out to afford the corresponding polyesters with narrow molecular weight distributions (weight-average molecular weight/number-average molecular weight < 1.3) quantitatively. Polymerizations with various feed ratios afforded the corresponding polyesters with predictable molecular weights and narrow molecular weight distributions. Kinetic studies of the polymerizations at -78 degreesC revealed that the polymerization rates were apparently larger than that of ethylphenylketene, which is considered to be responsible for the enhanced electrophilicities of the monomers via the introduction of electron-negative halogen atoms. Monomer conversion agreed with the first-order kinetic equation. These results strongly support the living mechanism of this polymerization. The obtained polyesters were modified by a palladium-catalyzed coupling reaction of the side-chain 4-halophenyl group with 4-methoxyphenylboronic acid, demonstrating their potential as reactive polymers.