This study is the first to investigate the anticancer effect of tricetin (TCN) in two human liver cancer cell lines, Hep G2 and PLC/PRF/5. TCN induced cancer cell death treatment by triggering mitochondrial and death receptor 5 (DR5) apoptotic pathways. Exposure of Hep G2 and PLC/PRF/5 cells to TCN resulted in cellular glutathione reduction and ROS generation, accompanied by JNK activation and apoptosis. Both of the antioxidants vitamin C and catalase significantly decreased apoptosis by inhibiting the phosphorylation of JNK and subsequently triggering DR5 cell death pathways. The reduction of JNK expression by siRNA decreased TCN-mediated Bim cleavage, DR5 up-regulation, and apoptosis. Furthermore, daily TCN intraperitoneal injections in nude mice with PLC/PRF/5 subcutaneous tumors resulted in an approximately 60% decrease of mean tumor volume, compared with vehicle-treated controls. Taken together, the results of the present study indicate that TCN-induced cell death in liver cancer cells is initiated by ROS generation and that both intrinsic and extrinsic apoptotic pathways contribute to the cell death caused by this highly promising cancer chemopreventive agent.