Stoichiometric hydroxyapatite (HAP) is a prominent biomaterial, notably used as coating on metal bone prostheses. High chemical purity and a specific particle size distribution are the main properties for such an application. Based on industrial practice, a reference synthesis was first performed in a lab-scale stirred reactor. Improvements were then suggested by varying the physicochemical and hydrodynamic conditions. The shear rate within the reactor, characterized by the mean Kolmogorov micro-scale, has a strong impact on the final agglomerate size distribution. By maintaining a rather high mixing rate and a high temperature, the duration of the synthesis can be reduced considerably without affecting the HAP purity provided the pH is properly regulated. This consists of imposing acidic conditions during a short period just after the initial formation of large aggregates and then setting the pH at above 7.5 to ensure the production of pure stoichiometric HAP. (C) 2019 Elsevier B.V. All rights reserved.