gamma-MnS nanocrystalline materials have been prepared by reaction of Na(2)[Mn(HL)(2)(H(2)O)(2)]; 1:2 (M:L) chelate complex with alkaline solution of thiocarbamide in aqueous solution phase. Effect of metal chelate complex, reaction time and surfactant sodium dodecyl sulfate: SDS on phase, morphology and size of the products have been investigated. The metal chelate complex was synthesized by reacting Mn(II) ions with eriochrome black T (NaH(2)L) in alkaline medium. gamma-MnS crystals were formed when metal complex was used as metal source whereas Mn(3)O(4) was the dominant product when MnSO(4)center dot H(2)O was used as metal source. Materials thus formed having various morphologies were characterized by X-ray diffraction, scanning electron microscopy (SEM), transmission electron microscopy (TEM) to determine the crystallinity, phase, structure and morphology. The optical properties of the thus prepared samples were determined by UV-vis absorption spectra and photoluminescence spectra. A possible formation mechanism of crystals has been discussed in this article. (C) 2011 Elsevier Ltd. All rights reserved.