Planar micro-supercapacitors are attractive for system on chip technologies and surface mount devices due to their large areal capacitance and energy/power density compared to the traditional oxide-based capacitors. In the present work, a novel material, niobium nanowires, in form of vertically aligned electrodes for application in high performance planar micro-supercapacitors is introduced. Specific capacitance of up to 1 kF m(-2) (100 mF cm(-2) ) with peak energy and power density of 2 kJ m(-2) (6.2 MJ m(-3) or 1.7 mWh cm(-3) ) and 150 kW m(-2) (480 MW m(-3) or 480 W cm(-3) ), respectively, is achieved. This remarkable power density, originating from the extremely low equivalent series resistance value of 0.27 Ω (2.49 µΩ m(2) or 24.9 mΩ cm(2) ) and large specific capacitance, is among the highest for planar micro-supercapacitors electrodes made of nanomaterials.