Synthesis, structures, and magnetic properties of ternary rare earth oxides ALnO 2 (A = Cu or Ag; Ln = rare earths) have been investigated. CuLnO 2 (Ln = La, Pr, Nd, Sm, Eu) were synthesized by the direct solid state reaction of Cu 2 O and Ln 2 O 3 , and AgLnO 2 (Ln = Tm, Yb, Lu) were obtained by the cation-exchange reaction of NaLnO 2 and AgNO 3 in a KNO 3 flux.These compounds crystallized in the delafossite-type structure with the rhombohedral 3R type (space group: R-3m). Magnetic susceptibility measurements showed that these compounds are paramagnetic down to 1.8 K. Specific heat measurements down to 0.4 K indicated that CuNdO 2 ordered antiferromagnetically at 0.8 K.3