Coaxial carbon nanotube-nickel hydroxide (CNT/Ni(OH)2) composites are prepared by a simple, one step and inexpensive chemical coprecipitation method. The coaxial coating of nickel hydroxide provides a three dimensional (3D) structure for easy access of electrolyte. Asymmetric supercapacitors (ASCs) are fabricated using coaxial CNT/Ni(OH)2 composites as positive electrode and reduced graphene oxide (rGO) as negative electrode. The operation voltage is expanded to 1.8V in spite of the use of aqueous electrolyte, revealing a high energy density of 35W·h·kg-1 at a power density of 1.8kW·kg-1. This strategy for choice of coaxial metal hydroxide CNT composites provides a promising route for next generation supercapacitors with high energy as well as power densities.