We report an investigation of the preparation, structure, and magnetic properties of ternary oxides containing copper in oxidation states-I, -II, -III, and -IV. The compounds described are: ACuO2(A = Al or Ga); AcuCo2(A = Ca, Sr, or Ba), A2Cu2O5(A = Sc, Y, Bi, or In), and A2CuO4(A = La, Al, or Ga); BaCuO2·5, ACuO3(A = Y or La); and BaCuO2·63 which is the only phase containing copper(IV) which could be obtained. X-Ray pcv.der patterns have been indexed wherever possible and magnetic-susceptibility measurements from 80 to 300 K are interpreted for all paramagnetic species.