Abstract: The present invention relates to a process for producing alcohol(s), according to which a culture medium containing a sugary carbon substrate (2) is introduced into a reaction section (1) comprising a support (4) on which micro-organisms are immobilised, in order to produce, by fermentation under the action of the said micro-organisms, a must (3) enriched with alcohol(s) and fermentation gas(es), such that the process is operated continuously in the liquid phase, and such that, in order to control production, the quantity of living micro-organisms immobilised on the support is monitored without intervention on the said supports.