Non-volatile memory cells employing a transition metal oxide layer as a data storage material layer are provided. The non-volatile memory cells include a lower and upper electrodes overlapped with each other. A transition metal oxide layer pattern is provided between the lower and upper electrodes. The transition metal oxide layer pattern is represented by a chemical formula MxOy. In the chemical formula, the characters “M”, “O”, “x” and “y” indicate transition metal, oxygen, a transitional metal composition and an oxygen composition, respectively. The transition metal oxide layer pattern has excessive transition metal content in comparison to a stabilized transition metal oxide layer pattern. Methods of fabricating the non-volatile memory cells are also provided.