There is provided a process for preparation of synthesis gas from feedstocks containing methane and/or higher hydrocarbons having from about 2 to about 12 carbon atoms by an initial catalytic treatment of feedstock to provide a methane-containing gaseous mixture substantially free of compounds having 2 or more carbon atoms, and reforming the gaseous mixture at elevated temperatures using nickel-containing catalytic materials that are unusually active under mild conditions of conversion and resistant to deactivation. The process consists fundamentally in converting the higher hydrocarbon compounds to form the methane-containing gaseous mixture in an initial conversion zone containing a catalyst while controlling temperatures within the initial conversion zone to temperatures in a range downward from about 500 C. to about 300 C., and reforming the methane-containing gaseous mixture in a subsequent zone to form synthesis gas.