The floating catalyst method for carbon nanotube production seems promising for scaling up since it enables continuous feeding of the catalyst to the reactor together with the carbon source. However, there are many experimental factors affecting the amount of nanotubes produced. Multivariate experimental design technique was utilized to determine the relative significance of selected factors at different levels. Temperature seems to be highly important for the amount of nanotubes formed, and catalyst content of the feed solution should be kept in a narrow range to increase the yield. Carrier gas flow rate should not be more than a certain level and hydrogen content of the feed should be at least 10%. Thiophene, on the other hand, seems to have little effect on yield thus may not be included in the feed solution.