The process uses microwave heating at 200 °C in acidic aqueous media to carbonize pine sawdust (Pinus sp.) and a-cellulose (Solucell®) at three different reaction times. Elemental analysis showed that the lignocellulosic samples subjected to MAHC yielded carbon — enriched material 50% higher than raw materials. In order to qualitatively evaluate the carbonization process, H/C and O/C were plotted using the van Krevelen (1950) diagram, which provides information about the changes in chemical structure after carbonization. These results showed that microwave-assisted HTC is an innovative approach to obtain carbonized lignocellulosic materials (Guiotoku et al., 2009).