Liquid film mass transfer coefficients in packed beds and strings of spheres were calculated theoretically using a penetration model for the mass transfer combined with the hydrodynamics of a laminar spherical falling film. The predictions were tested with packed beds varying in packing size from 0.006-0.058 m, bed height from 0.35-1.20 m, column diameter from 0.08-0.50 m; density of liquid from 996-1152 kg m(-3) and viscosity from 2.88-34.66 kgm(-1)h(-1). Strings of spheres tested varied in diameter from 0.0189-0.0381 m, number of strings from 1-3 and number of spheres per string from 1-20. The values of mass transfer coefficient obtained theoretically were in close agreement with the experimentally observed values.