Varnish wastes based on polyurethane were burnt in a laboratory scale furnace at different residence time of gases and temperatures and with a fuel-rich atmosphere and with an excess of oxygen. The yields of CO, CO2, six light hydrocarbons (methane, ethylene, etc.) and 31 semivolatile + volatile compounds (benzene, toluene, naphthalene, dibezofuran, etc,) were determined with stoichiometric: factors of the oxygen between 0.6 and 0.9, nominal temperatures of the reactor between 750-1050 degrees C and residence times of the volatiles evolved and formed between 2 and 6 s. The collection of the volatiles evolved was carried out with a Tedlar bag and by XAD-4 resin, comparing the data obtained in both cases. The maximum emission factors or yields of volatiles + semivolatiles were obtained at 850-950 degrees C, with values above 0.5% for benzene, naphthalene, acenaphthylene, phenantrene and fluoranthene. The thermal behaviour of different compounds was analysed. Naphthalene, benzene and toluene were also detected in the excess oxygen runs.