The reactions of the C2 unsaturated hydrocarbon radicals represent an important field of work that is relevant to macroscopic reaction media, such as combustion and environmental processes. The reaction kinetics and mechanisms of product formation of C2 unsaturated hydrocarbon radicals, namely, ethynyl (C2H), vinylidene (H2C=C), and vinyl (C2H3) radicals, are reviewed. The thermochemistry as well as the production and detection of these radical species are outlined. Results of relevant computational studies are discussed, and preferred rate coefficients for the radical reactions presented.