The evaporation of pyrolysis oil was studied at varying heating rates (similar to 1-10(6)degrees C/min) with surrounding temperatures up to 850 degrees C. A total product distribution (gas, vapor, and char) was measured using two atomizers with different droplet sizes. It was shown that with very high heating rates (similar to 10(6)degrees C/min) the amount of char was significantly lowered (similar to 8%, carbon basis) compared to the maximum amount, which was produced at low heating rates using a TGA (similar to 30%, carbon basis; heating rate 1 degrees C/min). The char formation takes place in the 100-350 degrees C liquid temperature range due to polymerization reactions of compounds in the pyrolysis oil. All pyrolysis oil fractions (whole oil, pyrolytic lignin, glucose and aqueous rich/lean phase) showed charring behavior. The pyrolysis oil chars age when subjected to elevated temperatures (>= 700 degrees C), show similar reactivity toward combustion and steam gasification compared with chars produced during fast pyrolysis of solid biomass. However, the structure is totally different where the pyrolysis oil char is very light and fluffy. To use the produced char in conversion processes (energy or syngas production), it will have to be anchored to a carrier. (C) 2010 American Institute of Chemical Engineers AIChE J, 56: 2200-2210, 2010