Freezing of a phase-change medium in a sealed, rotating cylindrical capsule was studied experimentally. The axis of rotation was either colinear with the axis of the capsule or perpendicular to the axis of the capsule, with corresponding maximum centrifugal forces of about 2g and 41/2g. The role of rotation differed depending on whether the capsule was fully or partially filled with liquid at the onest of freezing. For the fully filled capsule, rotation-related effects occurred only when the liquid was initially superheated relative to the fusion temperature. Rotation, acting via the Coriolis force, decreased the heat flow from the superheated liquid to the solid-liquid interface which, in turn, gave rise to a small increase in the rate of solidification and in the energy extracted from the capsule, with the net effect being no larger than 5 percent. In the perpendicular mode, rotation had a significant effect on the spatial distributions of the frozen layer thickness and of the voids. For the case of a partially filled capsule, rotation altered the position and shape of the air space associated with the partial filling and in this way gave rise to substantial increases (up to 17 percent) in the rate of solidification.