Biomass was gasified in a continuous stirred tank reactor (CSTR) at 500 degreesC and various pressures (30-50 MPa), reaction times (1.5-10.5 min), and dry matter contents (1.8-5.4 wt %) of the biomass. These results are compared with the results of experiments in a batch reactor, which was heated to 500 degreesC with two different heating rates (1 and 3 Ivmin) using two different dry matter contents (5 and 7.5 wt %). Key compounds for different reaction pathways, in particular phenols, were analyzed. The results concerning the dependence of the dry matter content on the gas formation, total organic carbon content, and phenols concentration are very different. In the CSTR the increase of the dry matter content leads to an increased gas yield, in particular of CH4, and the phenols yield increases. This was not found in the batch reactor. The possible reasons are discussed.