The bio-oil vapors produced from the pyrolysis of birch bark have been fractionated using a series of three condensers maintained at different temperatures. The temperatures of the condensers have been optimized in order to separate the water present in the bio-oil vapor stream from the organic phases and, consequently, increase the quality and the stability of the bio-oil. The condenser train consisted of an electrostatic precipitator-cum-condenser (C ESP) installed between two cyclonic condensers. As a result of the high efficiency of the fractional condensation system, the water content of the fractionated bio-oil was reduced to be less than 1 wt%. The effect of pyrolysis temperature on the fractionated bio-oil yield and characteristics is also reported. (C) 2014 Elsevier B.V. All rights reserved.