Transparent Y2O3 ceramics singly-doped with either Eu3+ or Tm3+ were fabricated by means of sequential consolidation steps at high pressure and temperature. These ceramics were characterized for their luminescence and thermal lensing behaviors, and the results compared to data on single crystals reported in literature. Thermal diffusivity, D, and conductivity, K, values of D=26×10-3 cm2/s and K=5.8 W/m K, respectively, for 1.0 mol% Eu3+ and 0.5 mol% Tm3+ singly-doped Y2O3 transparent ceramics were obtained. These values are about half of those for single crystal analogs. A small temperature coefficient of the optical path length change, ds/dT=3×10-6 K-1, was determined, making these materials suitable for applications requiring nearly athermal response. Selected spectroscopic properties were obtained by means of Judd-Ofelt analysis and together with thermal lens results provided absolute values for the fluorescence quantum efficiency of several levels, particularly 62% for the 5D0 level of Eu3+ and 84% for the 3F4 level of Tm3+.