A number of xanthotoxin-5-sulpho-derivatives 2a-c, 3a-c and 4a-e have been prepared by reaction of xanthotoxin-5-sulphonyl chloride (1) with amino-compounds or phenolic-com- pounds. The action of hydrazine derivatives on (1) have also been investigated. The interaction of hydrazine derivatives on xanthotoxin-5-sulphonamides 1, 2a and 4a has been discussed