As infrared observations have revealed, most of the ultra luminous IR sources are associated with interacting galaxies. AGN activity also appears to be more frequent in major mergers. The search of AGN in pairs of galaxies is not only important for the study of the origin of AGN activity (secular or merger induced) but is also relevant to the quest for super massive binary black holes (SMBBH), possibly triggering gravitational waves. We are analysing the X-ray emission in a well defined sample of major mergers in order to determine which parameters of the interaction are instrumental for the triggering of nuclear activity in one or both of the pair members: the mass of the galaxies, their separation and relative velocities, their morphological type, or the stage of the merging process. The sample is a subset of the nearby (z<0.05) close pairs of similar size galaxies of Arp-Madore for which Sekiguchi and Wolsencroft (1992) obtained optical and IR spectra.