A theoretical study of NO adsorption on $$\hbox {Cu}_{m}\hbox {Co}_{n}$$ (2 $$\le m+n \le $$ 7) clusters was carried out using a density functional method. Generally, NO is absorbed at the top site via the N atom, except in $$\hbox {Cu}_{3}\hbox {NO}$$ and $$\hbox {Cu}_{5}\hbox {NO}$$ clusters, where NO is located at the bridge site. $$\hbox {Co}_{2}\hbox {NO}$$ , $$\hbox {Co}_{3}\hbox {NO}$$ , $$\hbox {Cu}_{2}\hbox {Co}_{2}\hbox {NO}$$ , $$\hbox {Co}_{5}\hbox {NO}$$ , $$\hbox {Cu}_{2}\hbox {Co}_{4}\hbox {NO}$$ and $$\hbox {Cu}_{6}\hbox {CoNO}$$ clusters have larger adsorption energies, indicating that NO of these clusters are more easily adsorbed. After adsorption, N-O bond is weakened and the activity is enhanced as a result of vibration frequency of N-O bond getting lower than that of a single NO molecule. $$\hbox {Cu}_{2}\hbox {CoNO}$$ , $$\hbox {Cu}_{3}\hbox {CoNO}$$ , $$\hbox {Cu}_{2}\hbox {Co}_{2}\hbox {NO}$$ , $$\hbox {Cu}_{3}\hbox {Co}_{3}\hbox {NO}$$ and $$\hbox {Cu}\hbox {Co}_{5}\hbox {NO}$$ clusters are more stable than their neighbours, while CuCoNO, $$\hbox {Co}_{3}\hbox {NO}$$ , $$\hbox {Cu}_{3}\hbox {CoNO}$$ , $$\hbox {Cu}_{2}\hbox {Co}_{3}\hbox {NO}$$ , $$\hbox {Cu}_{3}\hbox {Co}_{3}\hbox {NO}$$ and $$\hbox {Cu}_{6}$$ CoNO clusters display stronger chemical stability. Magnetic and electronic properties are also discussed. The magnetic moment is affected by charge transfer and the spd hybridization. [ABSTRACT FROM AUTHOR]