Kinetic studies of hydrogenation reactions associated with an expertise in catalytic materials and surface science has permitted substantial progress in improving selective hydrogenation reactions. This has resulted in several new and improved hydrogenation catalysts. In parallel, research in process engineering aspects of hydrogenation reactions has enabled the rapid transformation of the knowledge gained in fundamental studies to industrial reality. Among the various hydrogenation processes on steam cracker or fluidized catalytic cracker olefinic feeds, three newly improved or developed catalysts and processes are detailed: propylene cut selective hydrogenation with a bimetallic catalyst, butadiene-rich cut selective hydrogenation to either 1-butene or 2-butenes by using tailored catalysts, and selective hydrogenation of FCC C4 and C5 cuts on a thioresistant catalyst.