A process and plant for air separation by cryogenic distillation. Air is cooled in a main exchanger and is sent to a distillation column in which it separates into an oxygen-enriched liquid and a nitrogen-enriched vapor. A stream of pressurized liquid coming from the apparatus vaporizes in the main exchanger. The refrigeration necessary for the process is generated by expansion of air in one or more turbines immediately downstream of the main exchanger. The turbine or turbines produces or produce, as output, a stream which is at least 95 percent liquid, preferably 100 percent liquid.