A process and an apparatus for atomizing a liquid hydrocarbon feed and injecting it into a reaction zone, such as a riser conversion zone or a dense fluid bed reactor of a fluid catalytic cracking unit, is disclosed. The hydrocarbon feed passes through a central passage with steam flowing concurrently in a concentrically aligned passage. By providing a flow restriction means in each hydrocarbon passage and each steam passage, substantially equal quantities of hydrocarbon and steam can be supplied to each of a plurality of hydrocarbon-steam nozzles so as to provide a uniform dispersion of small droplets of hydrocarbons.