We report infrared absorption measurements that provide evidence for the presence of boron carbide icosahedra in amorphous hydrogenated boron carbide thin films. The infrared absorption spectra are dominated by an intense line at 1280 cm−1 with a FWHM of ⋍ 320 cm−1. Similar lines have been previously reported in polycrystalline boron carbide, where boron carbide icosahedra make up the unit cell. In both systems, the linewidth narrows and the peak position shifts to higher energy with increasing carbon concentrations. From annealing studies of amorphous hydrogenated boron carbide, hydrogen plays a very small role in the 1280 cm−1 line. Finally, the integrated intensity of the 1280 cm−1 line is a sublinear function of the boron concentration, providing further evidence that the boron content of these icosahedra increases as the boron concentration of the film increases.