The effect of poly(ethylene-alt-maleic anhydride) (EMA), an additive used in nickel powder precipitation, has been studied using sodium hypophosphite as a reducing agent. Reduction experiments were conducted using a 10L stainless steel batch reactor. The effect of EMA was investigated by studying the evolution of the particle size distribution (PSD) and its derived moments, specific surface area, rate of reduction, pHredox potential and elemental composition of the powder product. EMA has been found to act as a reduction catalyst and anti-agglomerating agent. The major particulate processes identified were size dependent aggregation, molecular growth and breakage. (c) 2012 Canadian Society for Chemical Engineering