Catalyst is made by co-precipitating in the cold Ni oxide and Al2O3, shaping the precipitate, and reducing the Ni oxide. The Al2O3 may be partly or wholly replaced by another dehydrating or dehydrogenating oxide, for example, ThO2, blue oxide of W, TiO2, MgO. The catalyst may be prepared as described in British Patent 354,351. The CH4 reaction is preferably effected at 330°-400° and at atm. or slightly increased pressure.