The far—infrared reflectance and Raman scattering spectra have been measured on bulk and thin film samples of the infinite-layer ACuO 2 (A: alkaline earth) compounds. The reflectance spectra show four main bands, one of them possibly resolvable into two components. The Raman spectra display weak and broad features which shift in energy with the average ion size on the A 2+ site. Such features may result from multiphonon scattering.