Despite the advantages offered by gas lift reactors with respect to high gas-liquid mass transfer with a low energy input, their acceptance in the crystallisation field has been slow, especially on an industrial scale. Potassium chloride, potassium sulfate, and magnesium chloride hexammoniate (MgCl2 center dot 6NH(3)) were crystallised in a laboratory-scale gas lift crystalliser by salting-out using ammonia gas. Ammonia mass transfer rates were calculated for each test. To achieve maximum crystal growth, the gas rate in these reactors needs to be optimised for each crystallising system to achieve sufficient gas mass transfer as well as providing sufficient crystal slurry agitation.