The adsorption behavior of organic substances onto bubble surface in nonfoaming bubble separation was investigated. Experiments were conducted with a bubble column equipped with a droplet collector or a trap at its top. Crystal violet (CV) and humic acid (HA) were used as examples of surface-active substances. The amount adsorbed onto the bubble surface was calculated through the mass balance in the bubble column. Two adsorption parameters, equilibrium constant, K, and saturated surface density on bubble surface, gamma, were determined for CV and HA, respectively, by fitting of the experimental results to a Langmuir-type isotherm. Using the value of K, gamma and the intrinsic volumetric flow rate of droplets at the liquid-atmosphere interface, the variation of enriching ratio, E, with concentration of the solution was estimated and compared to the experimental results. The calculated E was in good accordance with the experimental ones for both CV and HA.