Ni6(N2H4)6(SO4)4(OH)2(H2O)8](SO4)(H2O)10 complex was prepared according to literature report. The reaction between aforementioned complex via sodium alkoxides as a reactants, were carried out in the solid state. The [Ni6(N2H4)6(SO4)4(OH)2(H2O)8](SO4)(H2O)10 undergoes an intramolecular two electrons oxidation-reduction reaction at room temperature and metallic nickel nanoparticles (Ni1-Ni5) was produced. The aforesaid complex contains nickel (II) as an oxidizing agent and also hydrazine ligand as a reducing agent. Its redox reaction leads to the formation of other products, sodium azide and ammonia gas and alcohols. In such a solid state reaction, not only the intramolecular redox reaction is important but also it is a novel method in the synthesis of nanoparticles. The nickel metal nanoparticles were characterized using X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and vibrating sample magnetometer (VSM) analysis. The synthesized nickel nanoparticles have similar morphologies however the particle size distributions are different. The nickel nanoparticles have particle size distributions ranging from 10 to 75 nm. This work presents a novel approach in the intramolecular redox reactions in the solid state, and provides insight into the synthesis of metal nanoparticles via metal hydrazine complexes at room temperature.