The dyeing properties of silk-fibroin with C.I. Reactive Red 22 and Red 8 were investigated by determining the apparent diffusion coefficient, apparent activation energy of diffusion, and adsorption and fixation quantities with the following results; The apparent diffusion coefficient of C. I. Reactive Red 22 within silk-fibroin was 4.65 $ imes$10-16$ extrm{cm}^2$/sec.~4.34 $ imes$10-12$ extrm{cm}^2$./sec. The apparent activation energy of diffusion was 11.4k.cal./mole~9.8k.cal./mole, varying inversely with change in pH. The adsorption and fixation quatities were maximized at pH 9.4 for C. I. Reactive Red 22 and Ph 5.9 for Red 8. The apparent diffusion coefficient of C. I. Reactive Red 8 within silk-fibroin decreased from 2.44 $ imes$10-12$ extrm{cm}^2$./sec. to 7.67 $ imes$10-13$ extrm{cm}^2$./sec. when sodium sulfate was added to the dye solution.