Aerogel catalysts (Ni/Al2O3 and Co/Al2O3) were prepared using a modified sol-gel method. Compared to catalysts prepared by conventional incipient wetness technique, the obtained aerogel catalysts showed higher activity, stability, and reproducibility. Approximate 79.2 and 64.7% of CH4 were converted in the presence of Ni/Al2O3 and Co/Al2O3 aerogel catalysts. Only 62.8 and 35.8% of CH4 were converted using conventional Ni/Al2O3 and Co/Al2O3 catalysts. Ni/Al2O3 aerogel catalyst can still show high catalytic activity with the CH4 conversion of 78.8% after five cycles. Carbon nanotubes (CNTs) were produced during the catalytic decomposition of methane and grown by tip growth or a mixture of tip and base. It was observed that the CNTs were grown by base growth in this study. Above results show that the preparation of aerogel catalysts is an effective strategy for improving catalytic performance by enhancing the specific surface area and pore structure, and is beneficial for obtaining CNTs for further applications.