In order to increase the stability of semiconducting metal oxides and to modify their gas sensing behavior, noble metal surface additives are often used. In literature, there are numerous papers that report the drastic effect of platinum loading on the sensing characteristics of WO₃. Here a thorough characterization of two different platinum loaded WO₃ samples was coupled with operando diffuse reflectance infrared Fourier transform spectroscopy. Based on the results, it was possible to identify the mechanism which is responsible for the changed sensor behavior. It was found that in this case a Fermi level pinning mechanism dominates. In addition, by comparing the two samples prepared with different impregnation methods, it could be shown that the dispersion on the surface of the material determines how strong the effect of the loading is. This work complements recent findings in which the Fermi level pinning mechanism was identified for Rh₂O₃ loaded samples (SnO₂, In₂O₃ and WO₃) and Pt-loadings on SnO₂. The results help in understanding reports already found in literature and provides useful inputs for the intentional tuning of sensor characteristics.