Besides hydrolysis of perfluoroorganosulfanesulfinylimines in closed systems, reactions of RfSxCl with K2S2O5 or M2S2O3 are also productive methods for the prepn. of perfluoroorganosulfanemonosulfonates. The free acid F3CSSSO3H is prepd. by treating the K salt with a strong acidic cation resin. It is unstable with pKa ~ -0,5 providing an acidity comparable wit polyphosphoric acids. Metatheses of the K salts with [Ph4M]Cl (M = P, As) or [R4N][ClO4] (R = Pr, Bu), resp., lead to well crystd. salts. Single crystals are used for x-ray structure anal. These prove the polysulfanesulfone-moiety to be present in these mols. S-S bonds can also be evidenced by chlorolysis. Not only with Cl2, but also with SCl2, RfSxCl or RfSx+1Cl and ClSO2OM are formed resp. In this way F3CSSSCl is prepd. for the first time. The reaction of F3CSeBr and K2S2O5 provides K[F3CSeSO3] which is unstable and decomps. to F3CSeSeCF3, K2S2O6, SO2, and KBr. When S2Cl2 is reacted with Me3SiNSO, besides the main product S2(NSO)2 also minor amts. of Sx(NSO)2 (x = 3-5) are formed. While hydrolysis of S2(NSO)2 leads quant. to (NH4)2S4O6, a mixt. of ammoniumpolysulfanedisulfonates is obtained from Sx(NSO)2 which could not be sepd. Chem. reactivity is dominated by disproportionation of S2(NSO)2 into S(NSO)2 and S. Addnl., sulfinylimines are obtained by metathesis of XNSO (X = Cl, Br) and AgSCN or AgSeCN, resp. The structures of S2(NSO)2 and OSNSCN are established by x-ray methods. According to spectroscopy, OSNSeCN is isostructured with OSNSCN.