The objective of this work is to study the reactive crystallization in an airlift-loop reactor (ALR) using the precipitation of Ni(OH)(2) as a model reaction. The growth of Ni(OH)(2) particles in an ALR and a stirred tank was quantified by scanning electronic microscope (SEM), X-ray diffraction (XRD), laser particle analyzer, tap densitometer and optical microscope, and the growth process of Ni(OH)(2) particles is analyzed. It is found that the Ni(OH)(2) particles prepared in an ALR have a better sphericity than those in a stirred tank and the growth of Ni(OH)(2) particle tap density mainly depends on the size of crystallites: the bigger the size of crystallites, the bigger the tap density is. Based on these, the growth process of Ni(OH)(2) particles in ALR is elaborated. Crystallites precipitated from solution aggregate to form large particles with much void. These constituting crystallites continue to grow up, that takes up the void inside particles and makes the tap density increase. (C) 2017 The Chemical Industry and Engineering Society of China, and Chemical Industry Press. All rights reserved.