Recently it was demonstrated that atomic oxygen can cause the extraction of substrate atoms off metal surfaces thus generating chemically different active sites. For Ag(110) this process occurs when O 2 is dosed at 175 K leading, at low coverage, to the formation of single Ag vacancies. Vacancy creation proceeds thereby via the formation of O-AgO complexes, which involve a local reconstruction of the surface and ignite the disruption of the Ag substrate. In this paper, we report on the details of such processes and on the isolated structures formed by the O adatoms in the limit of very low coverage. We employ scanning tunnelling microscopy and density functional theory to unravel the complex structures of O/Ag(110) which are transiently present under specific reaction conditions. A variety of features such as isolated grey dots, sombreros, shallow grey and white structures oriented along [001] and [11 0], grey stripes, and lozenges were identified and assigned to O adatoms in different configurations. The zigzag chains interact strongly with the STM tip and are easily disrupted, giving rise to highly mobile, sombrero shaped, isolated O adatoms also far away from the scanned area, i.e. from the current injection spot. Around 200 K, not only Ag vacancies, which are mobile with anisotropic migration, can merge together into rather complex features, but also the mobile Ag atoms are trapped by O adatoms, thus facilitating the formation of an oxygendecorated Ag chain along [001] which ultimately induces the well-known added row reconstruction.