Compounds of stoicheiometry (R4N)Cu(CH3CO2)2X (X = NCS, NO2, or Br) have been prepared and their spectral and magnetic properties have been studied. The infrared spectra of the compounds where X–= NCS– or NO2– are in agreement with co-ordination of these anions as isothiocyanato- and nitrito-groups, respectively. The compounds display antiferromagnetism, and it is suggested that the anions may have the dimeric structure of cupric acetate monohydrate, with the X– ions replacing the water molecules. The preparation of the compound Cu(CH3CO2)2·Ph3AsO is also reported, and this has a low magnetic moment at room temperature.