Multi-wall carbon nanotubes were synthesised from the catalytic decomposition of CO and CH4 on powder Co/La2O3 catalysts. TEM and HR-TEM, XRD, and TGA were used to characterise carbon nanotubes. It was found that by adjusting the composition of the catalysts, the size of the nanotubes was controllable and by annealing, the crystallinity could be improved. The carbon nanotubes produced from CO were found to be able to uptake a certain amount of hydrogen under ambient conditions, whereas graphite powders were unable, which suggests that the carbon nanotubes may be a promising material that can be used for hydrogen storage under ambient conditions.