Temperature-programmed desorption (TPD) of CH4, C2H6, C2H4, and CO and temperature-programmed pulse surface reactions (TPSR) of CH4, C2H6, C2H4, CO, and CO/H-2 over a Co/MWNTs catalyst have been investigated. The TPD results indicated that CH4 and C2H6 mainly exist as physisorbed species on the Co/MWNTs catalyst surface, whilst C2H4 and CO exist as both physisorbed and chemisorbed species. The TPSR results indicated that CH4 and C2H6 do not undergo reaction between room temperature and 450 degrees C. Pulsed C2H4 can be transformed into CH4 at 400 degrees C whilst pulsed CO can be transformed into CO2 at 100 or 150 degrees C. In gaseous mixtures of CO and H-2 containing excess CO, the products of pulsed reaction were CH3CHO and CH3OH. When the ratio of CO and H-2 was 1: 2, pulsed CO and H-2 were transformed into CH3CHO, CH3OH and CH4. In H-2 gas flow, pulsed CO was transformed into a mixture of CH3CHO and CH4 between 200 and 250 degrees C and was transformed into CH4 only above 250 degrees C.