The 'thermal deN0,' process using urea has been investigated in a 1 MW fluidized bed combustor. NO, reductions of up to 76% were obtainable by using this method. The experimental results show that urea is at least as active as NH,, which is commonly used in this application, but which is far more toxic and corrosive. Emission levels of 200 mg m -3 for NO, could be achieved by injecting the urea at a height of 2 m above the distribution plate in a molar ratio urea:NO,= 1.5. The SO2 emission value also appeared to be reduced when the urea was injected at a urea:NO, molar ratio ~4.