Pt/CeO₂catalysts are promising for the low temperature water gas shift (LT-WGS) which is an important step to produce H₂from syngas. When prepared by impregnation of platinum salt and calcination at 500 °C, they contain Pt$^{2+}$ single atoms (SAs) and/or PtO$_x$ clusters which need to be converted into Pt$^0$ nanoparticles (NPs) to get higher activity for the LT-WGS reaction. In this work, it was shown that reducing pretreatments at 250°C under H2 promote the molar activity of catalysts containing from 0.10 to 1.06 wt% of Pt by increasing the number of Pt$^0$ NPs formed during reaction at 230°C. An improvement was also obtained for pretreatment at 500 °C but only for low Pt content catalysts underlying the importance of the pretreatment temperature. Furthermore, it was shown that all prepared Pt/CeO₂catalysts which slowly deactivate over reaction time can be regenerated by oxidative post-treatment at only 230°C what is industrially interesting. Even more original, a strong improvement in activity was observed after a 12 h oxidative post-treatment at 500 °C for the low Pt content catalysts. This post-treatment was shown to redisperse and reoxidize Pt atoms into PtOx species different from the initial ones. Such species are highly reducible on the surface of CeO2 and easily transformed into active Pt0 NPs.