We are fabricating and examining nanocarbon derived electron emission devices, specifically, nanodiamond lateral field emission diodes. These novel microstructures provide interesting means of accomplishing electronics that are unaffected by temperature and radiation and have promise for high-speed and high-power applications with their small inter-electrode spacing and efficient emitter geometry. The characteristic properties of nanocrystalline diamond are favourable for lateral field emitters. In this work, we report the fabrication process advancement and field emission behavior of the nanodiamond comb-shaped field emitter array in diode configuration. The lateral diode design includes arrays of high aspect-ratio nanodiamond emitter fingers arranged in a comb-like structure with spacing as small as 2 μm from the nanodiamond anode. The 9000- fingered lateral field emission diode (8 μm anode-cathode spacing) exhibited a turn-on voltage of 60 V (threshold electric field: 7.5 V/μm) and a high emission current over ~ 25 mA at an anode voltage of 260 V (electric field ~ 32 V/μm).