Abstract: Viable fluids such as blood components are rapidly frozen in plastic or the like pouches for transportation and/or storage by placing a flat pouch slack filled with fluid between two substantially planar parallel restraining surfaces such as metal plates of greater perimeter than the flattened slack filled pouch which are rigid enough to prevent sagging of the pouch when it is vertically disposed and flexible enough to accommodate expansion of the pouch flat sides during the freezing operation. The restraining surfaces are retained against separation by retaining means applied against at least a portion of the outer surfaces of each pouch restraining means and the entire assembly is immersed in a cryogenic medium to rapidly freeze the fluid.