A memory cell and a process for manufacturing the same are provided. In the process, a first electrode layer is formed on a conductive layer over a substrate, and then a transition metal layer is formed on the first electrode layer. After that, the transition metal layer is subjected to a plasma oxidation step to form a transition metal oxide layer as a precursor of a data storage layer, and a second electrode layer is formed on the transition metal oxide layer. A memory cell is formed after the second electrode layer, the transition metal oxide layer and the first electrode layer are patterned into a second electrode, a data storage layer and a first electrode, respectively.