The microstructure of sputtered films of copper(I)bromide, CuBr, was investigated by X-ray diffraction, scanning electron microscopy and atomic force microscopy. The existence of sub-micron size grains and large cavern-like pores significantly enhance the specific surface of the films and their sensitivity to ammonia gas. Treatment with ammonia gas did not change the microstructure significantly; a modification of surface roughness can be related to surface reconstruction during ammonia adsorption.