The objective of this study is to compare the efficacies of powder activated carbon (PAC) and granular activated carbon (GAC) as amendments for the immobilization of volatile compounds in soil. Soil artificially-spiked with chlorobenzenes (CBs) was amended with either PAC or GAC to obtain an application rate of 1%. The results showed that the dissipation and volatilization of CBs from the amended soil significantly decreased compared to the unamended soil. The bioavailabilities of CBs, which is expressed as butanol extraction and earthworm accumulation, were significantly reduced in PAC and GAC amended soils. The lower chlorinated and hence more volatile CBs experienced higher reductions in both dissipation and bioavailability in the amended soils. The GAC and PAC equally immobilized more volatile CBs in soil. Therefore, it could be concluded that along with environmental implication, applying GAC was the more promising approach for the effective immobilization of volatile compounds in soil.