Electrochemical discharges in aqueous solution of sulphuric acid and ethanol as scavenger of hydroxyl radicals, in addition to polyvinylpyrrolidone as stabilizing agent are used for the synthesis of nano-sized nickel oxide colloids. Morphological characterization by electron microscopy and powder X-ray diffraction has been performed to examine the obtained particles at different terminal voltages and experiment durations. From the qualitative resemblance of the electrochemical discharges to the radiolysis technique, a microscopic mechanistic model is proposed giving an overall picture of the physicochemical phenomenon for the synthesis of fine particles. (C) 2011 Elsevier Ltd. All rights reserved.