Technetium(I) and rhenium(I) hexacarbonyl cations were prepared for the first time at atmospheric pressure and room temperature by treatment of dichloromethane or chloroform solutions of [99TcBr(CO)5] and [ReCl(CO)5] with carbon monoxide in the presence of dry aluminum trichloride. The yield was 17.0 % and 3.1 %, respectively.