The technique of proton-enhanced 13 C n.m.r. has turned out to be a useful tool for the study of composition and structure of whole coals. In particular, four functional types of carbons can be resolved and recognized in studies on model compounds and a series of coals: polycondensed aromatic, simple aromatic, oxygen-bonded aliphatic and simple aliphatic. The principles of the techniques are described and examples given of application to model compounds, aromaticity of coals and coal processing by-products, and time-resolved changes in carbon distribution during coal processing.