Transition metal carbides can act as efficient metal-like catalysts or catalyst supports, and MXenes offer renewed possibilities to anchor metal atoms and promote catalytic performances. Herein, we report on the elaboration of Pt/MXene single-atom catalysts and their performance in CO2 and alkadiene hydrogenation reactions. Anchoring of single Pt atoms is favorable at the surface of Ti3C2Tx and Mo2Ti2C3Tx MXenes. According to in situ XAS and XPS, Pt cations partially reduce upon thermal treatment at 400 °C in H2 flow, while forming bonds with surface M atoms of the MXene. This includes the probable location of Pt atoms at M vacancies or Pt-M substitution, consistently with STEM. In addition, XAS, XRD and TPR reveal MXene restructuring together with desorption of chemical intercalants and terminal groups. While Ti3C2Tx is inactive, Mo2Ti2C3TX exhibits significant catalytic activity for both reactions. The addition of single Pt atoms on Ti3C2Tx leads to unusually high selectivity to 2-butene from butadiene hydrogenation [Mater. Today Catal. 2023, 2, 100010]. For CO2 hydrogenation, Pt/Ti3C2Tx shows a high Pt-molar activity and almost 100% selectivity to CO; Pt/Mo2Ti2C3TX is even more active, while methane and methanol are formed as minority products.