PbBiSrCaCuO films with a predominant Bi2Sr2Ca2Cu3O10 superconducting phase were prepared on (100) MgO and LaAlO3 substrates. The radiative properties of the film-substrate composites were investigated at room temperature and at temperatures near Tc in the wavelength band of 2 - 17 micrometers . For the film parameters used in this experiment, the near normal-incidence values of the reflectance were large while those of the transmittance were very small. No significant change in reflectance was observed as the film underwent a superconducting-normal transition in the vicinity of Tc. However, the reflectance decreased with decreasing film thickness and radiation wavelength. It could be verified that the substrate has a negligible effect on overall radiative properties when film thickness is sufficiently large. To determine the response mode of the film at infrared wavelengths, photoresponses to short laser pulses were measured. From the temperature- dependent behavior of transient structure and responsivity, the thermal origin of the photoresponse could be confirmed.