We have studied the hydrogenation of the non-polar a-planes of 4H-SiC. Surface hydrogenation was carried out by annealing the samples in an atmosphere of ultra-pure hydrogen. The surfaces were characterized by low-energy electron diffraction, photoelectron spectroscopy and Fourier-transform infrared absorption spectroscopy. The spectroscopic results are discussed in the light of our earlier studies on the H-terminated basal planes of 6H-SiC and structural models are developed.