We measured the reduced mobilities of the atomic, Ne + , and dimer, Ne 2 + , ions in Ne, under different pressures and reduced electric fields, at 300 K. The value obtained for the atomic ion, 4.1 cm 2 V -1 s -1 , is in good agreement with other values published in the scientific literature. The value obtained for the mobility of the dimer ion, 7.3 cm 2 V -1 s -1 , is not in accordance with other published data. We discuss the most probable sources of error.