[en] Russian scientists have recently succeeded in cooling and compressing hydrogen until it became a conducting metal at a pressure of a few megabars and at a temperature of 4.2 K. Experimental details are given and the many difficulties which face the workers in this field such as the possible superconductivity of the material, methods of stabilizing the material, production of a large volume of the material and investigation of the crystalline structure of the material, are discussed. Reasons for the interest being shown in metallic hydrogen are considered. (U.K.)