Three cascade processes for the simultaneous production of hydrogen and carbon nanotubes (CNTs) were designed about the catalytic decomposition of methane (CDM), overcoming the conflicting requirements of carbon generation, transfer, and deposition rate for the generation of hydrogen and CNTs. NiFeAl and FeMg, were selected as catalysts for the generation of hydrogen and CNTs, respectively. In individual testing, the hydrogen yield of CDM with NiFeAl reached 55%. However, with FeMg, the CNTs yield reached 0.95 g/g(cat) when the co-fed hydrogen ratio, V-CH4:V-H2, was 10:20. The multiple connection mode, including one NiFeAl stage and two FeMg stages, was the most promising system for the production of pure hydrogen with 86% yield and high-quality CNTs with 2.63 g/g(cat) output. This cascade CDM process is applicable and promising for large-scale industrial hydrogen and CNTs production through utilizing existing catalysts of CDM further. (C) 2020 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.