Zinc sulphide nanoparticles in the size range ∼10–40 Å diameter have been synthesized using the aqueous chemical method. Scanning tunneling microscopy showed that particles are indeed nanosize particles. The size dependent band gap could be varied from a bulk value of 3.68 to 4.5 eV. X‐ray diffraction indicated that nanoparticles are crystalline except for those with band gap ∼4.5±0.1 eV. Nanoparticles with particle size ∼21×2 Å diameter or energy gap 4.1×0.1 eV were doped with manganese. The photoluminescence peak at ∼600 nm corresponding to yellow light emission was observed. Atomic absorption studies show that maximum luminescence intensity is achievable with 0.12 at. wt % of Mn doping.