Considering the important and various application of copper nanoparticle, in this thesis a novel method for synthesis of these particles via disproportional approach were investigated. In this project a solution of Cu+ was prepared via ISET mechanism and then copper prticles were precipitated through a disproportion reaction. To minimaze the size of the prticles the effect of many factors such as concentration and pH were investigated. Other factors such as sodium laurate as a surfactant and nonionic polymer, polyethylene glycole, on particle size were studied and it was found that the sodium laurate concentration has a significance influence on lowering the size of particles. Another method for synthesis was carried out via a two phase environment without using surfactant and resulted to very smaller particles and narrowing the distribution range. In the second part of this project dispersion of synthesized particles in various fluids such as water, ethylene glycol, oil engine and trans oil were carried out. Oleic acid as a stabilizing agent was added to nanofluid in trans oil and ethylene glycol to improve the particle dispersion behavior.