An ultraviolet spectrometer was used to measure the absorption kinetics of a laser dye, 1,4-bis(5-phenyloxazoyl-2-yl) benzene, at its maximum wavelength in solutions of styrene-acrylonitrile copolymer dissolved in 1,4-dioxane. From the time-dependent absorbance data, the dye diffusion coefficient was calculated by a combination of Fick's law of diffusion with the Beer-Lambert law of absorption. (C) 2005 Wiley Periodicals, Inc.