Hydrodimerization is an organic reaction that couples two alkenes to give a symmetrical hydrocarbon.  The reaction is often implemented electrochemically; in that case the reaction is called electrodimerization. The reaction can also be induced with samarium diiodide, a one-electron reductant.
Hydrodimerization is the basis of the Monsanto adiponitrile synthesis:
:2CH=CHCN  +  2e  + 2H   →  NCCHCHCHCHCN
The reaction applies to a number electrophilic alkenes (Michael acceptors).