To synthesize polymer-grade propylene from bioethanol containing an organosulfur compound such as dimethylsulfide (DMS) or dimethylsulfoxide (DMSO), we examined the adsorptive desulfurization of propylene by employing commercial activated alumina. It was found that both DMS and DMSO were converted predominantly to hydrogen sulfide during the catalytic conversion of ethanol to propylene over HZSM-5 zeolite. The performance of the adsorbent was evaluated by measuring a packed-bed breakthrough curve for the adsorption of hydrogen sulfide in gaseous propylene. Because of the adsorptive desulfurization, the concentration of hydrogen sulfide in propylene could be reduced to less than 10 ppb.