A continuous process for the dehydrogenation of paraffinic and olefinic hydrocarbons in the presence of a catalyst comprises circulating a charge containing said paraffinic hydrocarbons through at least two reactions zones of the moving bed type which are arranged in series, the catalyst flowing successively in each reaction zone. The catalyst which is drawn off from the last reaction zone is sent to a regeneration zone at the exit from which it is reintroduced close to the first reaction zone. The process comprises the injection of sulphur and/or at least one sulphur compound before or simultaneously to the introduction of the charge into the first reaction zone. In accordance with the process, the catalyst which is drawn off from the last reaction zone is sent into a stripping zone wherein the sulphur which it contains is removed before the catalyst is sent to the regeneration zone.