In this work, we obtained samples of carbon-containing materials from fibrous residues of rice husks and straw, husks of soybean and sunflower, cedar shells at temperatures of 300, 400, and 500 °С. The ash content (3.0–9.3%), the content of water-soluble substances (1.2–7.6%), the mass fraction of moisture (3.0–6.2%), and the pH values of the aqueous extract (5.4– 8.8) and bulk density (66–481 kg/m3) were determined. The IR spectra of carbon-containing materials from plant materials contain more pronounced bands of oxygen-containing functional groups in comparison with medical preparations and BAH coal. The samples are in an X-ray amorphous state, and with increasing firing temperature, the degree of carbon ordering networks increases. All samples have a layered fiber structure, which differs depending on the type of raw material and temperature. The sorption activity was studied with the respect to iodine (7.6–58.4%), methylene blue (4.2–35.8 mg/g) and methyl orange (5.2–64.4 mg/g), which changes depending on the type of raw material and the temperature of carbonization. It was shown that with an increasing firing temperature, the sorption activity of the samples increases. Samples obtained at 500 °C have a high iodine absorption capacity (50.8–58.4%), comparable with BAH activated carbon (60%), and can be used as inexpensive porous carbon materials.