The present manuscript presents the application of X-ray computed microtomography (microCT) as a non-intrusive technique to calculate the local and global mass transfer rates around arbitrary shaped particles. The technique is validated on the case of mass transfer around a spherical particle in free convection. A review of available experimental and numerical investigations for spherical particle is reported in comparison to the obtained results. The 3-dimensionality of the microCT approach allows the calculation of the local curvature. The correlation between local curvature and mass transfer rate is, therefore, made experimentally feasible for arbitrary shaped particles.