Abstract: This invention relates to a process for cracking hydrocarbon feedstock comprising a mixture of ethane and propane by (a) subjecting the feedstock to a fractionation process so as to separate the feedstock into an ethane rich stream and a propane rich stream, (b) steam cracking each of these streams separately under optimum cracking conditions for each stream in separate furnaces, (c) recovering the ethylene so formed in said crackers and (d) recycling the residual uncracked ethane and propane from the cracked products to the respective ethane rich and propane rich feedstreams being fed to the steam cracker. The process enables yields of ethylene to be increased.