Five parameters - rotational speed, temperature, molar calcium-to-aluminium ratio, aluminium hydroxide source, and water-to-solids ratio - were tested. Their degree of influence on the balance of formation between katoite and hydrocalumite (HC), the extent of reaction, and the product crystallinity were investigated. It was found that the conversion to HC can be increased by increasing the rotational speed from 400 rpm to 1000 rpm or by using a larger stirrer bar at the same rotational speed. The conversion to HC can also be increased by providing calcium hzdroxide and aluminium hydroxide at a ratio of [2:1] and ensuring a reaction temperature between 80 °C and 90 °C. Katoite formation was favoured at low rotational speeds and supply of the stoichiometrically correct molar ratio of calcium hydroxide and aluminium hydroxide ([3:2]), and was increased at 90 °C. Significant amounts of unreacted calcium hydroxide remained in the product at calcium-to-aluminium ratios other than [3:2]. Unreacted reactants also remained in the product at temperatures lower than 60 °C. The product crystallinity could be increased with an increase in crystallinity of the aluminium hydroxide source. Other tested parameters had a lesser or negligible effect on the product crystallinity.