An　efficient　electrochemical　approach　for　the　C(sp(2))-H　phosphonation　of　quinoxalin-2(1H)-ones　and　C(sp(3))-H　phosphonation　of　xanthenes　has　been　developed.　The　chemistry　was　performed　in　an　undivided　cell　under　constant　current　conditions　and　features　a　wide　range　of　substrates,　up　to　99%　yield　and　it　is　free　of　transition-metal　catalysts-　and　external　oxidants,　thereby　providing　a　straightforward　approach　for　dehydrogenative　C-H/P-H　cross-coupling.　In　addition,　control　experiments　disclose　that　some　of　the　reactions　may　involve　a　radical　pathway.