A novel way to synthesize cubic PbS quantum dots (QDs) with average sizes of about 3 nm to 5 nm is presented in the current research. A mixture of sodium dodecyl sulfate (SDS) and cetyltrimethyl ammonium bromide (CTAB) was used as stabilizing agent and ethylene diamine tetraacetic acid (EDTA) was used as dispersant in the chemical bath synthesis method. The role EDTA that plays in the fabrication of PbS QDs was also analyzed. PbS QDs could not be synthesized without EDTA even with the use of stabilizing agents SDS and CTAB. EDTA facilitates the formation of stable complex compounds with Pb2 + metal ions and prohibits the aggregation of PbS QDs.Highlights►A novel way to synthesize PbS QDs has been developed by chemical bath method. ►The size of the QDs is about 3 nm to 5 nm with good monodispersity. ►EDTA plays a dual role in the fabrication of PbS QDs. ►PbS particles instead of PbS QDs are formed without EDTA.