The spinodal decomposition apparatus was built in our laboratory for foaming the polymers via spinodal decomposition method. Mostly the open-cell microfoams are prepared by this method. The apparatus (Figure 1a and 1b) consists of a stainless steel vessel (D) with a thread for screwing on to the stainless steel top (A) and with a flange to attach to the bottom. Between the top and the bottom of the vessel two O-rings are placed (C, E) to ensure a sufficient sealing. The bottom of the mould (F) is from the copper sheet. As additional insulation can be used a Teflon cylinder (B). This arrangement enables the heat transfer to be one-dimensional.