The present application provides a hydrodefluorination process for the preparation of hydrofluoroalkenes by catalyzed substitution of one or more F atoms of a C2-C30 fluoroalkene, or a C2-C10 fluoroalkene, with one or more H atoms using a hydride source, such as a silane, and copper catalyst. During this process at least one C—F bond in the fluoroakene is converted to a C—H bond. The process is useful in the manufacture of hydrofluoroalkenes, such as hydrofluoroalkenes employed as, for example, refrigerants and blowers. Also provided are precatalyst compositions for performing the process, and formulations manufactured from hydrofluoroalkenes produced using the process.