Abstract: Process for the manufacture of coarse aluminum hydroxide, containing a maximum of 15 weight percent of the particles in a particle size under 45 micrometers, with a productivity that may be higher than 60 grams of precipitated Al.sub.2 O.sub.3.The process consists of a decomposition in two stages (an agglomeration phase and a growth phase); each stage proceeding within defined temperature ranges with seed material of different constitution. The first (fine) seed amount is added at the start of the decomposition in such an amount, that the ratio of the supersaturation of the aluminate liquor to the surface area of the seed hydroxide per liter of the aluminate liquor presented for decomposition exhibits a value of 7 to 25 grams per square meter. The process exhibits the advantage of the high productivity of the so-called European process and the advantage of the so-called American process by obtaining a coarse product hydroxide.