Magic-size nanocrystals of cadmium selenide showing yellow-light emission were synthesized in a single-step spray pyrolysis process at 150 °C. An organoselenium precursor dissolved in N,N-dimethyl formamide was introduced via a syringe pump and the droplets were decomposed in hot solution of cadmium oleate. The ratio of Cd:Se precursor, the process temperature at which the decomposition is carried out and the co-formation of quantum dots play critical role in unique optical property of yellow-light emission.Research highlights► Green non-toxic method. ► Self-doping of magic-size nanocrystals with quantum dots. ► Yellow emission.