Abstract: The invention concerns a method for preparing an epoxide, in particular glycidol, wherein a cyclic organic carbonate, in particular glycerol carbonate, is heated under reduced pressure so as to carry out a reaction to contract the carbonate ring into an epoxide ring. According to the present invention, the reaction is carried out in a solid/liquid system in the presence of a polyol and a solid catalyst consisting of a type A zeolite or &ggr;-alumina. The method, which may be carried out continuously, enables the epoxide to be formed in a single step, the epoxide being exhausted in the form of vapor which only has to be extracted and separated from the carbon dioxide formed.