Absolute efficiency and modulation transfer function of laboratory prepared La2O2S:Tb phosphor screens of various coating thickness were studied. Detailed experimental data on the variation of absolute efficiency with x-ray tube voltage up to 200 kVp and screen coating thickness in transmission and reflection observation mode are given. Data were compared with similar results from other rare earth phosphor materials. Theoretical calculations were in good agreement with experimental data to permit estimation of intrinsic efficiency and coefficients related to light scattering and absorption within the phosphor material. The MTF of La2O2S:Tb screens was also experimentally and theoretically evaluated.