While the nature of the lattice oxygen activation is not fully understood its occurrence is generally aligned with the ability of the system to form and stabilize surface oxygen vacancies . This rationalization of the LOER mechanism should be universal and its occurrence can be tested computationally e.g. by DFT calculations of surface stabilities and construction of Sabatier-type volcano plots . Surprisingly, the computational approach towards LOER has, to our knowledge, not yet been extended beyond Ni based perovskites. This paper aims at extending this fundamental computational approach to modelling the behavior of OER catalysts in acidic media -namely of the ruthenium dioxide and substitutionally doped ruthenium dioxide.