Polychlorinated dibenzo-p-dioxins（PCDDs) and dibenzo-p-furans（PCDFs) are ubiquitous environmental contaminants，which persist and bioaccumulate through the food chain. Formation mechanisms of PCDD/Fs in thermal processes are rather well-documented in the literature. Precursor pathways and de novo synthesis are considered as two general formation pathways. Metal-catalyzed formation from phenol precursors is one of the widely studied precursor pathways. However，most studies of the phenol condensation pathway have been performed using highly chlorinated phenols，such as pentachlorophenol. As existed naturally，catechol is structurally simple，with two adjacent hydroxies attached to the molecular backbone，and can usually be extracted from passion flowers and fruits. In this research，we investigate PCDD/Fs in CuCl2-catalyzed formation from catechol at 300 ℃. PCDD/F congener patterns in the formation are shown in Figure 1.