In this work, the catalytic decomposition of the minor hydrocarbons present in natural gas, such as ethane and propane, over a commercial carbon black (BP2000) is studied. The influence of the reaction temperature on the product gas distribution was investigated. Increasing reaction temperatures were found to increase both hydrocarbon conversion and hydrogen selectivity. Carbon produced by ethane and propane was predominantly deposited as long filaments formed by spherical aggregates with diameters on the order of nanometres. Furthermore, the influence of ethane and propane on methane decomposition over BP2000 was also investigated, showing enrichment in hydrogen concentration with the addition of small amounts of these hydrocarbons in the feed. Additionally, the positive catalytic effect of H2S on methane decomposition over BP2000 is addressed. (C) 2008 Elsevier B.V. All rights reserved.