Abstract The degree of structural order in the organic carbon preserved in grey–black shales of the Neoproterozoic Torridon Group was characterized using Raman spectroscopy. All the samples contained kerogen rather than graphite, which is consistent with a low level of metamorphism. Samples of shale from the Diabaig Formation from six widely separated localities exhibited a consistently greater structural order than shales from five localities in formations higher in the Torridon Group. This supports previous models invoking an unconformity between the Diabaig Formation and the rest of the Torridon Group. The data further suggested that the Diabaig Formation experienced an additional episode of heating in the late stages of Grampian deformation.