The aqueous concentrations of oils, fuels and solvents resulting from riverine spills are highly dependent upon the dissolution rate coefficients, on which there is little information available. The water-film mass transfer rate coefficient was measured for the dissolution of a hexane slick in a stirred cylinder and in an oscillating grid chamber. In both devices, the turbulence was generated beneath the oil-water interface, similar to the bed-generated turbulence in rivers. The liquid-film coefficient was also measured during reaeration studies, conducted without a surface slick under the same conditions. In comparing the coefficients measured with a slick and without, the presence of the surface slick was found to have minimal impact on the water-film mass transfer coefficient after indexing properly with the Schmidt number. Thus, the dissolution rate coefficient for any compound can be easily predicted from the reaeration rate coefficient for a given river reach. Additionally, no scale effects were detected between the between the 4 L stirred cylinder and the 87 L oscillating grid chamber.