A thorough molecular characterization is crucial for the quality control of polycarbonates (PCs), since their physical properties are dictated by the chemical nature of end-groups and/or repeating units. The high-molecular-weight of PCs prevents their direct characterization by MALDI-TOF mass spectrometry (MS). Instead, an “on-plate degradation” sample pretreatment developed for polyesters is proposed for the analysis of PCs. In a two-step method, a methanolic solution of sodium hydroxide is first added to high-molecular-weight samples deposited on a MALDI target plate. Polymer chains are rapidly and selectively cleaved at the carbonate ester bonds, producing short oligomers of under m/z 3000, readily observed by high-resolution MS. The characterization of chain-ends of a PC homopolymer and of the repeating units of a PC copolymer exemplify the capabilities of the procedure for a fine evaluation of molecular features. A low amount of 4-cumylphenyl terminus at a relative abundance of ∼4 %, compared to the t-butylphenyl terminus, is indeed successfully detected. It is also demonstrated that tetrabromobisphenol A, together with bisphenol A, are the two main components forming a copolymeric backbone, rather than a blend of homopolymers. For this second example, a Kendrick mass defect (KMD) analysis greatly facilitates the extraction and assignment of peaks from brominated species having complex isotope patterns in the mass spectrum.