The concentrated stable aqueous solution of water soluble reactive dyes with substantial desalting could be achieved by cellulosic based asymmetric nanofiltration membranes. In this paper, the modification and performance of an in-house developed nanofiltration membrane for its efficiency in simultaneous desalination as well as concentration of reactive dyes is evaluated both in flat-sheet and spiral wound configuration. It has been observed that the chemically modified nanofiltration membranes are far more efficient than unmodified membranes in their performance with respect to their dye rejection, salt permeation and solution flux under identical operating conditions.