The refractive indices of BaF(2) thin films have been determined experimentally in the 1-11-microm wavelength range. They are found to be significantly lower than the corresponding bulk values and to vary markedly as a function of the deposition rate. A quarterwavelength optical thickness layer of BaF(2) is shown experimentally to be an effective single-layer antireflection coating for NaCl and KCl surfaces at 10.6-microm wavelength and to have a high damage threshold for high-power cw CO(2) laser radiation.