A process for the recovery of lithium hydroxide from lithium sulfate containing solutions, the process characterised by the following method steps:



precipitating ettringite from a lithium sulfate containing solution in a primary ettringite precipitation step (100);
subsequent recovery of a liquor (7, 11) containing lithium hydroxide; and
producing a lithium hydroxide monohydrate product (22) from the lithium hydroxide liquor (7, 11).