Unchained Reaction is a science and engineering reality game show that aired on the Discovery Channel. It was judged and executive-produced by Adam Savage and Jamie Hyneman, best known for hosting the science entertainment series MythBusters.

The series premiered on March 18, 2012. The show pits two teams of various backgrounds against each other to build an elaborate chain reaction contraption (sometimes also referred to as a "Rube Goldberg" machine or device). Teams are provided with identical sets of tools and materials and are given five days to construct a series of mechanisms based on a predetermined theme. Midway through each week, the teams are provided with a surprise "missing link" item that they must add to the middle of their machines. The winner would be selected by Savage, Hyneman, and a guest judge.