In this research, mono-dispersed quantum dots of CdSe were produced using a phosphine-free approach to synthesis of colloidal quantum dots. Selenium precursor was selected as the main precursor. It was found that the initial concentration ratio of monomers critically controlled the size distribution of the nanoparticles through its influence on the growth kinetics of these particles. The best result was obtained using an initial Se/Cd ratio of 5 where CdSe quantum dots of a uniform size were synthesized. This was manifested in the absorption spectra of these particles by occurrence of sharp peaks at a wavelength of about 615 nm.