This study evaluated the effect of thermophysical properties of heat carriers on the performance of a laboratory scale auger reactor. Heat carriers tested included stainless steel shot, fine sand, coarse sand and silicon carbide. The results showed similar organic yield and composition of bio-oil among the heat carriers when pyrolyzing red oak. Significant differences in yields of reaction water, char and non-condensable gases were observed. It was also found that residual carbon contributed to as high as 20 wt% of total char yield and attrition of heat carrier as high as 7% on a mass basis were present after as little as 2 h of operation. Tradeoffs between physical performance, material cost, and product yields may exist when selecting heat carrier materials for pyrolysis of biomass in an auger reactor.