An improved method of preparing deuterated alkanes from the halides has been developed. Dehalogenation of ethyl iodide, 1,1-dibromoethane, and 1,1,1-trichloroethane with zinc dust in deuterium oxide – dioxane solutions, or even with deuterium oxide alone, gave excellent yields of ethane-d1, ethane-1,1-d2, and ethane-1,1,1-d3. Methane-d1, -d2, -d3, and -d4 were prepared similarly from methyl iodide, dibromomethane, chloroform, and carbon tetrachloride respectively. The isotopic purity of the products was over 90 mol.%. The reaction is also applicable to higher alkyl halides.