Fast pyrolysis of sugar cane vinasse, a byproduct from the integrated sugar ethanol process, has not been investigated so far. In this work, fast pyrolysis of dried sugar cane vinasse was carried out at 400 and 500 degrees C in a drop-tube type N-2-purged reactor, and the yields and compositions of the oil, char, and gas were determined. The results show that the water free bio-oil yield was low and independent of the pyrolysis temperature. This is probably due to the high potassium content of the vinasse. For other biomass fuels, it is well established that alkali metals catalyze secondary reactions in the vapor-phase of the pyrolysis product, thereby reducing the organic liquid yield and increasing the gas and water yields. The char yield decreased, and the gas yield increased with temperature. 45% to 55% of the carbon in the vinasse was retained in the chars. Thus, approximately half of the carbon in the vinasse could be sequestered if the chars are returned to the soil. Moreover, since over 85% of the potassium in the vinasse was also retained in the chars, pyrolysis may be an interesting option for the production of biochar with a high potassium content for fertilizer. The recovery of most of the potassium with the chars indicates that the liquid and gaseous pyrolysis products could be burned in a boiler with lower ash-related problems than the original vinasse.