Three surface-nitrogen removal processes, i.e. (i) N2O(a) -> N-2(g) + O(a), (ii) N2O(a) -> N2O(g), and (iii) 2N(a) -> N-2(g), were separately analyzed in a steady-state NO + CO + O-2 or NO + H-2 reaction on Pd(110) through angular and velocity distributions of desorbing products. Processes (i) and (ii) are predominant at low surface temperatures, whereas process (iii) becomes major at high surface temperatures. (c) 2004 Published by Elsevier B.V.