The macromolecular components of two humic brown coals of the same moor-facies type, but different geological age were isolated, and their structures were subsequently characterized using solid-state C-13-NMR spectra. The results were compared with the published C-NMR data of the macromolecular components of a brown coal which was rich in liptinite macerals. As to the humic coals, the proportion of the macromolecular components is smaller in the older coal than in the younger coal (65% and 85%, respectively). The NMR spectra show a structure which is related to lignin structures. Quantitative differences are indicated by the smaller proportions of aliphatic oxygen functionalities and the higher proportions of alkyl groups in the older coal. The macromolecular components of the liptinitic brown coal represent a completely different structural type: Their network has an aliphatic basic structure and is predominantly built up by linkage of methylene chains. Very differentiated structural conditions exist for microbial depolymerization of the macromolecular structures of brown coals.