A catalyst and process is described for the conversion of hydrogen and one or more oxides of carbon in which the catalyst comprises an elemental carbon-containing support. Also described is a process for reducing agglomeration in carbon nanotubes, in which carbon nanotubes are suspended in a liquid and simultaneously treated by ultrasound and agitation. The method can be used to prepare carbon nanotube-supported catalysts that show high activity towards the conversion of feedstocks comprising hydrogen and one or more oxides of carbon.