The effect was studied of using in-situ catalyst based on a HZSM-5 zeolite in flash pyrolysis with an inert gas (N-2) of sawdust of pinus insignis in a conical spouted-bed reactor in the 400-500 degrees C range and for a gas residence time of 50 ms The use of the catalyst increases the yield of gases and decreases the yields of liquid and char. Likewise, the yield of CO2 decreases, whereas the yield of C4- hydrocarbons increases (15.9 wt. % at 450 degrees C). The catalyst is efficient for partial deoxygenation of the liquid product.