Water dispersible Zn(1-x)MnxS solid solution photocatalysts stabilized with L-aspartic acid were synthesized by coprecipitation. Their photocatalytic activity was evaluated using methylene blue as a model pollutant. X-ray diffraction and Raman spectroscopy indicated the catalysts had a cubic crystal structure. The gradual increase in zinc sulphide (ZnS) lattice constant with increasing Mn2+ dopant concentration was due to the high ionic radius of Mn2+. Raman spectra exhibited two peaks at 260 and 345 cm(-1). Ultraviolet-visible absorption spectra of the catalysts exhibited a strong excitonic peak at 270 nm, which was blue shifted compared with that of bulk ZnS (340 nm). This was attributed to quantum confinement and coupling effects. The hydrophilic L-aspartic acid on the photocatalyst surface had a positive effect on photocatalytic activity. The effects of dye and dopant concentrations on photocatalytic activity were investigated. (C) 2014 Elsevier B.V. All rights reserved.