Biomass is a renewable, carbon-neutral and easily available source of raw material for obtaining energy and various other products. Pyrolysis enables the conversion of biomass into valuable by-products, such as biogas and bio-oil with a special emphasis on biochar. Its diverse application is the subject of many studies, while recently the possibility of using bio char as a precursor for the production of graphene has been examined. The purpose of this work was to find the most optimal raw material and process conditions on a laboratory scale in order to reduce the formation of dioxins and furans and obtain the highest possible yield of biochar as the desired product. After preliminary results obtained using gas analysis, calorific value, elemental analysis and heavy metal analysis, the selected sample "Oak" was subjected to pyrolysis on a semi-industrial scale at 800 ⁰C. The obtained biochar was modified with the aim of obtaining graphene oxide in two ways. Part of the sample was subjected to the Hummers method, and part to persulfate intercalation of graphite material. The thus intercalated sample was placed in a muffle furnace to further expand thermally. The results of the morphological, structural and electrochemical analysis showed that all samples have a graphite structure with free π-electrons, while the sample modified according to Hummers has the greatest potential for further processing. It has the simplest chemical composition, the most ordered structure and the largest contribution of hybridized sp2 bonds.