2-Hydroxycinnamaldehyde (HCA) and curcumin have been reported to have antitumor effects against various human tumor cells in vitro and in vivo by generation of ROS. Aldehyde-free HCA analogs were synthesized based on the structure of curcumin, which we have called 2-hydroxycurcuminoids. The hydroxyl group of curcuminoids enhances the ability to generate ROS. 2-Hydroxycurcuminoid (HCC-7) strongly inhibited the growth of SW620 colon tumor cells with a GI50 value of 7 μM, while the parent compounds, HCA and curcumin, displayed GI50 values of 12 and 30 μM, respectively. HCC-7 was found to induce apoptosis through the reactive oxygen species-mitochondria pathway and cell cycle arrest at G2/M phase.