Compared with EDLCs, pseudocapacitors use a transition metal capable of forming a complex by charging and discharging electrons through a redox reaction. Ni(OH)₂-based pseudocapacitors prepared by hydrothermal, sol-gel, and PVD methods exhibit high theoretical capacity and thermal stability. Electrodeposition is easy and fast, and the material can grow uniformly. In this study, we investigated the effect of Hexamethylenetetramine on the structure and capacitance characteristics of Ni(OH)₂ pseudocapacitors. Ni(OH)₂ formed on the nickel foam with a three dimensional structure and exhibited high electrical conductivity and porosity. In addition, the effects of HMT addition on the Ni(OH)₂ structure and the electrochemical properties of the supercapacitors were investigated; HMT is the source of amine-based OH- in the Ni nitrate solution and causes the formation of the three-dimensional structure. Moreover, the effect of HMT on the growth behavior of Ni(OH)₂ was analyzed from the resulting nanosheet structure. When electrodeposited at a constant voltage mode of -0.85 V vs Ag/AgCl, the addition of (up to 7.5mM) HMT reduced the cathodic current and accelerated the nucleation rate, resulting in a dense Ni(OH)₂ structure on the nickel foam. Under these electrodeposition conditions, a capacitance was of 1174.392 F·g^-1 , and the a maximum energy density was of 69.129 mWh·g^-1 were achieved.