Pyrolysis of flax straw was investigated under a nitrogen atmosphere using a tubular reactor at different pressures, ranging from 10 to 40 psi. The effects of pressure on the pyrolysis yields and the products obtained (gas, liquid, char) have been analyzed. The gaseous products were analyzed by online GC, and the bio-oils were characterized by gas chromatography/mass spectrometry (GC/MS). Scanning electron microscopy (SEM) was used to view the char surfaces in order to characterize the char and validate the presence of porosity. As the pyrolysis pressure increased, the yield of char and liquid decreased while the gas products increased. The gas products were mainly CO, H-2, CO2, CH4, and C-3's. The bio-oils were mostly composed of phenolic compounds, carboxylic acids, and furfural. The pH and the density of the bio-oil revealed a moderate increase with increasing pressure. The SEM study confirms the porous nature of the char. Overall, bio-oil production was maximized at 10 psi; however, char and hydrogen production was maximized at 20 psi.