15N-induced nuclear reactions on H and D have been used to study hydrogen and benzene adsorption on Ni(111) in a UHV system connected to a Van de Graaff accelerator and equipped with surface cleaning facilities. Analysis can be performed in vacuum or in a gas atmosphere which is of particular interest for molecules with a low sticking probability like H 2. The coverage of hydrogen on the Ni surface has been measured in the 10 -8-10 -2 mbar pressure range taking into account the contribution of the nuclear reactions induced on hydrogen atoms in the gas phase for pressures higher than 10 -5 mbar. When the analysis is performed after gas evacuation (H 2 or C 6H 6) an ion-induced desorption effect can be observed and a low irradiation fluence is required (integrated charge of 1 μC) setting a detection limit of 7.5 × 10 13 at/cm 2. Working with or without gas pressure points out for C 6H 6 a second phase reversibly adsorbed on the surface. In the coadsorption study with labelled molecules (C 6D 6H 2 or C 6H 6D 2) the nonresonant nuclear reactions on deuterium allow to analyse deuterium without interference from hydrogen and a detection limit of 2.2 × 10 14 at/cm 2 is obtained at a 8 MeV incident energy. The variation of the D concentration on the surface precovered with benzene as a function of hydrogen exposure, points out an exchange reaction between adsorbed molecules.