Clathrates (I) comprising a cysteamine component (II) and a cyclodextrin component (III) in a (II):(III) molar ratio of 1:0.5-15 are new, where (II) is selected from cysteamine and its salts and derivs. and (II) is selected from substd. or hydrated alpha -, beta - and psi - cyclodextrins. Also claimed are pharmaceutical compsns. with 'anticystinotic, radioprotective or radioprotective activity' contg. (I) as active ingredients or excipients. Also claimed are cosmetic compsns. with 'radio-protective activity' contg. (I) as active ingredients or excipients. (I) are prepd. by: (a) reacting an aq. soln. of (III) with an organic soln. of (II) and isolating (I) by filtration; or (b) reacting (II) with (III) in an aq. medium and drying or freeze-drying the resulting soln.