Graphitic-diamond heterostructure may be very helpful not only for high frequency or power devices but also for new generation of electronic devices like single electron transistors or quantum computers operated at room temperature. The goal of our work was a formation of nanothin amorphous carbon or graphite layers with sp3 or sp2 hybridization inside the nitrogen doped synthetic monocristalline diamond by high dose hydrogen implantation. It was found that there is a “critical” dose of 50 keV hydrogen molecular ions equal to 4x1016 cm-2 above which an irreversible drop of the sheet resistivity in implanted layer occurs after annealing above 1000 oC. The nature of this conductivity was investigated and it was shown that variable range hopping mechanism of 3D conductivity dominates in investigated temperature interval. Four times higher value for the onset of this conductivity in comparison with “critical” dose for graphitization is explained by interaction of implantation induced defects with nitrogen atoms and surface defects.