Theoretical computations of a series of clusters [Mo6Cl8(H2O)(n)(OH)(6-n)](n-2) are presented. UV-Vis absorption spectra, the ground states (S-0) and the lowest excited states (S-1 and T-1) were examined. Energy diagrams for luminescent decay were built in order to get insights about the emission processes of these systems. The fact that the systems show different emission energy profiles when the aqua and hydroxo coordinations are changed, indicates pH-dependence and supports the statement that these clusters are candidates to act as pH-sensors. Those properties are also shown by a reported family of luminescent [Re6S8(H2O)(n)(OH)(6-n)](n-4) clusters, with the same structure of the systems studied here. (C) 2013 Elsevier B. V. All rights reserved.