Acid infusion of lignocellulosic biomass as a pretreatment prior to fast pyrolysis has been shown to significantly increase the yield of sugar in the products. However, under these conditions char formation increases forming large agglomerates that clog the reactor and eventually interrupt operation of the system. In the present study, partial oxidative pyrolysis of acid infused red oak was performed in a fluidized bed reactor at 500 degrees C with the concentration of oxygen in the sweep gas ranged from 0 to 8.4 vol% in an effort to mitigate char agglomeration. The addition of oxygen reduced char agglomeration by up to 88.9% compared to the control run during pyrolysis ensuring continuous run of the reactor. Moreover, the addition of oxygen increased the total sugar content in the bio-oil to as high as 20.62 g/100 g biomass. Stage fraction 1 (heavy fraction) of bio-oil obtained from oxidative condition contained up to 67% of hydrolyzable sugar and it was less acidic compared to standard pyrolysis. (C) 2014 Elsevier Ltd. All rights reserved.