Photochromic polysulfones were synthesized by condensation between carboxypolysulfone (degree of substitution DS = 0.74) and functional photochromes (spiropyrans SP and spirooxazines SO) carrying amino, spaced amino, or spaced hydroxy groups. The synthetic methods needed to find an optimal path to satisfy the requirement of maximal photochrome concentration, maintaining sufficient chromophore mobility in the polymeric matrix, and avoiding polymer gelation, so that suitable membrane casting properties were maintained. The three-step strategy of (1) preblocking with auxiliary group (octylamide), (2) attachment of photochrome, and (3) postblocking is certainly cumbersome and suffers from partial removal of the attached groups, yet in essence provides material that satisfy the demands set out.