A gravimetric method was developed to study alumina dissolution kinetic by following the evolution of the apparent weight of alumina samples while immerged into a cryolithic bath. It is the change of the gravity and buoyancy on the sample that can help to determine the dissolution rate. The experimental results obtained by this method were compared to four other values; those found in the literature, a CFD model developed by our team, the total mass difference over experience time and finally to a boundary displacement method.