Fourier transform-infrared photoacoustic spectroscopy (FT-IR/PAS) and X-ray diffraction (XRD) techniques have been used to study the reduction of copper (II) oxide supported on mordenite zeolite, through the adsorption of carbon monoxide and hydrogen gases at 723 K. It was found that bands due to the bridged hydroxyl groups (3614–3630 cm−1) and the Al-OH groups (3780–3787cm−1) show significant changes upon carbon monoxide and hydrogen adsorption whereas the Si-OH band did not change after the adsorption. Two further bands were detected at 2156 and 2297 cm−1, assigned to carbon monoxide adsorbed on Cu+ species and on the copper-aluminate species, respectively. XRD patterns have demonstrated the proposed interaction between Cu2+ with aluminium mordenite, to form aluminate, whereas FT-IR spectra have established an interaction between carbon monoxide molecules and the aluminate species.