The invention relates to a process for the preparation of reactive cyclodextrins, in which process the cyclodextrins CD are reacted with a bifunctional alkyl compound X—(CH2)n—Y, wherein X is a group which reacts with CD, n is an integer from 2 to 20 and Y is a group which reacts with a group Z or is a group-Reactive which is capable of reaction with cellulosic or proteinic materials and, optionally, in a further step, insofar as Y is a group which reacts with a group Z, the resulting product is reacted with a reactive anchor compound Z-Reactive to form the reactive cyclodextrin, and also to reactive cyclodextrins prepared in accordance therewith, to materials dressed therewith and to the use thereof.