Pd/TiO2 catalysts were found to enter an strong metal support interaction (SMSI) state after reduction at temperatures as low as 473 K. This was identified as a significant loss in the CO uptake as monitored by low temperature FTIR. Electron microscopy provides direct evidence of the presence of ordered, reduced titanium oxide layers over palladium (SMSI state) for Pd/TiO2, catalysts following reduction at temperature 623 K. The crystal phase was identified as Ti4O7 and this phase, once formed, was found to be stable even after exposure to atmospheric conditions.