The evaluation of the mass transfer coefficient value (h) in a marker-capsule system, is proposed as a supplementary method for the characterization of gel beads and. microcapsules with semi-permeable membranes. This is intended to complement accepted techniques and indicators used in the determination of diffusion coefficient and molecular mass cut-off (MMCO). Mass transfer coefficients of a neutral, low molecular mass marker, Vitamin B-12, have been estimated for various alginate beads and polyguanidine-alginate-cellulose microcapsules with diameters (D) between 0.25 and 2.0 mm. These were experimentally determined to be in the range of 0.003-0.041 cm/min, dependent on size of the investigated capsule sample. Due to a good linear correlation between mass transfer coefficient and capsule diameter, each investigated type of capsule could be characterized by a unique h/D value, lying between 0.058 and 0.136 min(-1) and independent of the actual capsule size. Experimentally determined h/D values uniquely characterize mass transfer rate, at least for Vitamin B-12, for a selected capsule type and enable an objective ranking of encapsulation materials and standardization of measurements of transport properties in non-equilibrium state.