"Honeycomb"-type packings made of various materials were investigated. Absorption of ammonia in aqueous sulfuric acid solutions was used as the model system. The effective packing surface area was evaluated as the ratio of the volumetric mass transfer coefficient to the same coefficient obtained for values above the critical point where the packing surface was fully wetted. The liquid viscosity was changed by using sugar solutions and was varied between 1 and 10.3 mPa.s. It was shown that increasing the liquid phase viscosity results in up to 1.8 times growth of the effective surface of "honeycomb"-type packings at rather low values of the liquid superficial velocity. The experimental results are described by two equations, one for plastic and other for ceramic packings. The proposed equations can also be used to determine the critical point after which the packing is completely wetted.