The temperature and supersaturation dependencies of gibbsite crystal growth rates in caustic aluminate solutions were experimentally investigated in both the laminar (Taylor-Couette precipitator) and turbulent (stirred tank) mixing regimes. The gibbsite precipitation experiments were conducted batchwise in a temperature range from 55degreesC to 90degreesC, but all with the same initial liquor composition and seed type. At low supersaturation it was found that gibbsite crystal growth could be described satisfactorily by a screw dislocation growth mechanism over the complete temperature range, irrespective of the flow regime. At higher supersaturation and lower temperatures, i.e. 55degreesC and 60degreesC, it is proposed that two-dimensional polynuclear growth is the dominant growth mechanism in turbulent flows. Any differences observed in the measured growth rate estimates from the laminar and turbulent systems were explained by error analysis. (C) 2003 Elsevier B.V. All rights reserved.