The formation of cationic astatine compounds with thiourea, thiourea derivatives and some N-acylthioureas was investigated in aqueous solutions. The ion mobilities in free electrolytes were determined for the detection of carrier-free astatine compounds and their characterization. Informations about the stability of this group of compounds could be given after investigations in the presence of halogenide and pseudo halogenide ions /Cl–, Br–, I–, SCN–/. First results on the reaction of At//+ with thiourea derivatives and N-acylthioureas in acid and neutral solutions are reported. The cationic astatine compound formation with representatives of this group is shown.