The effect of temperature and gas residence time on the formation of 16 priority PAH from the ethanol pyrolysis, in the 975-1475 K temperature range, has been evaluated. Soot was quantified by weight difference of the collection filter and light gases were measured by gas chromatography and microchromatography. The PAH quantification was done by gas chromatography-mass spectrometry (GC-MS). The toxicity of the effluent was determined by the B[a]P-eq value with the concentration of the PAH found during the experiments. The principal results show that the PAH concentration presents a maximum with the temperature, which is shifted to lower temperatures as the gas residence time increases. The PAH with the highest concentration are: NAPH, ACNY, PHEN, FANTH and PYR, and they are mainly present adsorbed on soot. The highest toxicity, B[a]P-eq, of the effluent was found for the highest residence time, t(r)(s)= 4168/T (K), particularly on soot.