Discovering new candidate p-type transparent conducting oxides has become a major goal for material scientists. Combining the native p-type conductivity of Cu2O with the larger band gaps of other binary oxides, ternary Cu-based delafossite materials have attracted much attention since Hosono and co-workers first reported the optical and electrical properties of copper aluminate (CuAlO2). The Cu(I)-based delafossite structure, Cu(I)M(III)O2, can accommodate a wide range of rare earth and transition metal cations on the M(III) site. These ternary semiconductors exhibit more flexible properties arising from their enhanced chemical and structural freedoms. [2-5]In this poster we report a density functional theory investigation of Cu(I)M(III)O2 (where M(III) represents a range of trivalent metal ions), examining the stability and electronic structure using GGA corrected for on-site Coulomb interactions in strongly correlated systems (GGA U). From analysis of the calculated formation energies, band structure and density of states, we present predictions of new compounds in the family of delafossites. 1 H. Kawazoe, H. Yasakuwa, H. Hyodo, M. Kurita, H. Yanagi, and H. Hosono, Nature London 389, 939 (1997).2 J. E. Jaffe and A. Zunger, Phys. Rev. B 28, 5822 (1983).3 Y. Meng, X. Yang, H. Chen, J. Shen, Y. Jiang, Z. Zhang and Z. Hua, Thin Solid Films 394, 219 (2001).4 S. Chen, X. G. Gong, and S.-H. Wei, Phys. Rev. B 75, 205209 (2007).5 D.O. Scanlon, K.G. Godinho, et al, The Journal of Chemical Physics 132, 024707 (2010)