This paper developed a methodology to estimate 3D faceted crystal growth rates from 2D images obtained on-line from a single 2D camera. The cooling crystallisation experiment of potash alum was conducted in a small hot stage reactor. The promising results obtained provided a valuable alternative for the accurate estimation of faceted crystal growth rates, which are crucial to the performance of morphological population balance modelling and model-based control of crystal shape and size. (C) 2012 Elsevier B.V. All rights reserved.