The results of the physical and chemical studies of the organic matter of Devonian brown coals and rocks with carbonized plant residues from Northern Timan (Russian Arctic) are presented. We used a complex of physical and chemical methods, including IR spectroscopy, EPR spectroscopy, quantitative chemical analysis, pyrolytic gas chromato-mass spectrometry. For comparative studies we used Devonian (Middle Timan) and Jurassic (Griva, Komi Republic, Russia) carbonized plant residues and lignins, isolated from modern wood and non-wood plants. Organic structures of aromatic nature, which are products of the metamorphic transformation of lignins of coal-forming plants, were found in the investigated samples. It was shown that lignin’s relics show pronounced paramagnetic properties, mainly due to the presence of phenoxyl radicals. The concentration of paramagnetic centers reaches a value that is close to the maximum value nорг for carbonaceous substances. Based on quantitative analysis of phenolic products of pyrolysis the composition of lignin relics was calculated, taking into account the ratio of the main structural H, G and S units. Experimental data allowed to put forward the hypothesis that in the composition of Devonian coal-forming plants, as one of the first representatives of forest communities on the planet, included compositionally homogeneous protolignins of H-type, built mainly from p-coumaric structural units.