results on changes in s. c. d. of the cotton fibers dyed with reactive dyes have been reported. in general, the s. c. d. decreased as a result of the reaction between dye and fiber, the decrease being proportional to the concentration of the dye in the fiber. these results have been explained on the basis of the reduction in the effective surface area of the fiber responsible for the electrokinetic phenomena as a result of the reaction between fiber reactive dye. results on correlation between the s. c. d. and the zeta potential revealed that there is a linear correlation between the two parameters in case of all the dyes studied. for a bifunctional reactive dye, however, a separate linear plot was obtained. on extrapolation the linear plot representing the bifunctional dye passed through the origin, while the extrapolated linear plot for the monofunctional dye gave a positive intercept on the zeta potential axis. in case of the bifunctional reactive dye, on the other hand, such -oh groups on the cellulose chain are brought nearer to each other due to the formation of crosslinks between two cellulosic chains, thus inducing h-bond formation between them, in addition to the bridge formation through the bifunctional dye molecule. these results have been confirmed by comparing surface area available for nitrogen adsorption in case of fiber containing equivalent quantities of the monofunctional and the bifunctional reactive dyes. 6 refs