Coal tar was heat-treated at high pressures to separate water dispersed in it. Various samples of coal tar were bottle-tested at 383, 403, 423, and 443 K in dewatering closed systems. For fresh coal tar from coke ovens and for water-added coal tar, dewatering behaviors were studied under both saturated pressure and elevated pressure by adding noncondensable inert gas over saturated gas. The experimental data of the destruction and growth of aqueous dispersed phase were correlated with demulsification models by adjusting two model parameters. Coal tar tends to be easily dewatered when it is heat-treated under saturated pressure without preaddition of water. This work strongly suggests the existence of relationship between the phenomena of dewatering and boiling in coal tar.