A method is described for the protection of solid alkali metal samples for x-ray diffraction. Examples are given for the preparation and application of a film of polymer to cover the sample. The method has been successfully used for the x-ray diffraction of transition metal wires coated with solid sodium and for powder samples in a matrix of sodium. The technique may be applied to a wide range of compounds and elements which due to their physical and chemical properties may not be handled in the usual manner.