Disclosed herein are a platinum-based catalyst for oxidation/reduction reactions and the use thereof. The platinum-based catalyst is prepared by loading a catalyst composition comprising a water soluble salt of at least one metal selected from among cerium (Ce), zirconium (Zr) and rhenium (Re), on a support comprising at least one selected from among alumina, silica and titania. The disclosed catalyst can be prepared in a simple manner without any particular limitation as to the kind of usable water soluble platinum salt, and when it is applied to various oxidation reactions, including water gas shift reactions of carbon monoxide, three-way catalytic reactions, and selective oxidation reactions of carbon monoxide, and to reduction reactions, such as reactions of removing nitrogen oxide (NOx), it will show excellent catalytic activity. In particular, the disclosed catalyst shows excellent performance even in a specific temperature range in which it is difficult to apply the prior high-temperature water gas shift reaction catalyst and low-temperature water gas shift reaction catalyst. Also, it can remove carbon monoxide even at high temperatures without the loss of hydrogen caused by methanataion, and thus is particularly useful in a hydrogen production process of producing high-purity hydrogen for fuel cells.