Tetrakis(methyl cyanide) complexes of Cu(I), Cu(II), and Zn(II) fluorosulfates have been prepared by reactions of anhydrous Cu(II) and Zn(II) fluorosulfates in methyl cyanide. The infrared spectra indicate a strong interaction between the fluorosulfate anion and the complex Cu(II) and Zn(II) cations. Conductivity measurements in methyl cyanide show strong association between the fluorosulfate anion and the dipositive cations. The Cu(I) compound is completely dissociated in methyl cyanide and, according to the infrared spectrum, shows no strong interaction with fluorosulfate anion.