In article results of comparative studying of structure of humic acids of peats of a various origin of Tomsk area are resulted by a method of infra-red spectroscopy. It is shown, that IR-spectra of the humic acids taken from different types of peat, have a high degree of similarity that specifies affinity of their chemical structure. It is established, that humic acids low-moor woody-grassy type of peat have rather significant differences from other types of peat and represent connections with a high share aliphatic fragments and it is possible a smaller degree benzenoid, and also with the high contents of active sour groups (carboxylic, hydroxyl).