In this work, a response surface methodology (RSM) was used to study the effects of temperature (A), feed rate (B) and gas flow rate (C) on the liquid yield, char yield and pH of the biocrude oil. Box-Behnken design was chosen and a total number of 15 experimental runs including 3 center runs were generated for the pyrolysis of a mixture of 50 wt.% layer manure and 50 wt.% loblolly pine wood shavings in a 50 mm bubbling fluidized bed reactor. The operational variables were as follows: temperature (400-550 degrees C), nitrogen gas flow rate (12-24 L/min), and feed rate (160-480 g/h). A second-order regression models were used to predict the responses. The analysis of variance (ANOVA) was performed with Minitab 16 software and the significant effect of the factors and their interaction effects were tested at 95% confidence interval. The biocrude yield was significantly influenced by temperature, feed rate and gas flow rate. Temperature was the only significant factor that influenced the char yield. Maximum biocrude yield (51.1 wt.%) was achieved at 475 degrees C with a feed rate of 480 g/h and a gas rate of 12 L/min. The lowest char yield (22.6 wt.%) was achieved at 550 degrees C, 320 g/h and 12 L/min and the biocrude had the highest pH (4.85) at 475 degrees C, 160 g/h and 24 L/min. The predictive models proposed agreed with the experimental values. (C) 2011 Elsevier Ltd. All rights reserved.