Effects of temperature, concentration of thiourea and reaction conditions (thermal heating and microwave irradiation) on morphological properties of ZnS particles obtained by sedimentation from 0.01, 0.1 and 1 M zinc nitrate solutions are studied. It is found that ZnS particles of two shapes are formed from thiourea solutions at a thermal heating (70-90 degrees C): agglomerated particles of the spherical shape with the dimensions of agglomerates 50-100 nm (particle size in agglomerates of 3-5 nm) and hexagonal columns in length up to 2 mu m and diameter of 80-100 nm. At the microwave heating conditions (90 degrees C), irrespective of thiourea concentration formation of spherical ZnS particles with the size 0.6-1.2 mu m is observed. (C) 2013 The Society of Powder Technology Japan. Published by Elsevier B. V. and The Society of Powder Technology Japan. All rights reserved.