This dataset includes experimental and numerical data from the manuscript 'Dual ion species plasma expansion from isotopically layered cryogenic targets', published in Physical Review Letters. This is the data obtained during the investigation of a novel ion acceleration scheme using cryogenic targets, where a heavier ion (deuterium) exists at the target vacuum interface of a lighter ion species (hydrogen). Using this target configuration, it is found that the lighter ions interact with the heavier ions to accelerate a reduced energy spread, directional, heavy ion beam. Please see the file named ‘description_of_data’ in the root directory of the attached zip file for a detailed discussion of the data contained therein.EPSRC: EP/J003832/1, EP/K022415/1, EP/R006202/1, EP/G054940/1, EP/G055165/1, EP/G056803/1 NSFC: 11375262 and 11520101003.