Synchrotron-based Fourier transform infrared micro-spectroscopy (SR-μFTIR) was used to map photo-oxidative degradation of acrylonitrile–butadiene–styrene (ABS) and to investigate the presence and the migration of additives in historical samples from important Italian design objects. High resolution (3×3μm2) molecular maps were obtained by FTIR microspectroscopy in transmission mode, using a new method for the preparation of polymer thin sections. The depth of photo-oxidation in samples was evaluated and accompanied by the formation of ketones, aldehydes, esters, and unsaturated carbonyl compounds. This study demonstrates selective surface oxidation and a probable passivation of material against further degradation. In polymer fragments from design objects made of ABS from the 1960s, UV-stabilizers were detected and mapped, and microscopic inclusions of proteinaceous material were identified and mapped for the first time.