Mass transfer within a microcapsule is enhanced by convection, achieved by introducing a movable body inside the microcapsule. This body has a different density from the fluid within the microcapsule and can be moved relative to the microcapsule by application of an external force, such as a magnetic field or acceleration/deceleration. The effect of the transport improvement was investigated as a function of the Peclet number (Pe) by using computational fluid dynamics and particle image velocimetry. The results show that the period to achieve 80% saturation in the microcapsule was reduced by 60% with a movable body with half of the diameter of the microcapsule and Pe = 600, compared to the mass transport in the microcapsule with a non-movable body.