Gas absorption enhancement of gas-liquid slug ow by adding non-porous ne particles into the liquid phase was investigated. A glass tube with a millimeter-size diameter was used as the ow channel, and the gas and liquid slugs were air and distilled water, respectively. When the absorption rates of oxygen with and without the addition of nonporous silica ne particles in water were compared by the liquid-side mass-transfer coe cient, k L , the rate with particles was enhanced and increased as the concentration and diameter of the particles increased. This is because the frequency of particle circulation in the liquid slug increased at higher concentration, and the larger particles caused stronger disturbances at the boundary layer at the interface on the liquid-phase side.