Cobalt nanowires with high aspect ratio have been synthesized via a solvothermal chemical process. Based on the shape anisotropy and orientation of the nanowire assemblies, a record high room-temperature coercivity of 10.6[emsp14]kOe has been measured in Co nanowires with a diameter of about 15[emsp14]nm and a mean length of 200[emsp14]nm. As a result, energy product of the wires reaches 44[emsp14]MGOe. It is discovered that the morphology uniformity of the nanowires is the key to achieving the high coercivity and high energy density. Nanowires of this type are ideal building blocks for future bonded, consolidated and thin film magnets with high energy density and high thermal stability.