The Ca-doped gamma-La2S3 (gamma-La2S3:Ca) powders with various La/Ca ratios were prepared using the coprecipitation method. The gamma-La2S3:Ca powders with a ratio of La/Ca=5 was selected for sintering in order to study the effects of hot-pressing temperature and time on the microstructure and optical properties of gamma-La2S3:Ca ceramics. The results showed that 1100 degrees C for 1 h were the optimum hot-press parameters, at which the maximum transmittance of gamma-La2S3:Ca ceramics up to 40% at 13 mu m was obtained.