Display Omitted Metal ion ReRAM are preferred due to the high window and low variability.Material/programming algorithm optimizations enable high endurance and retention.Fully integrated cell on a 16Gb chip at 27nm have been demonstrated.Several challenges are highlighted to enable sub-10µA reliable operations.Cross-point architectures could enable high-density but require adequate selector. Resistive random access memory (ReRAM) devices are emerging candidates for the next generation of nonvolatile high-density memory (Sills et al., 2014). The value proposition for this technology is bit alterability, high speed operation, long retention and high endurance. In addition, low-power and low-current operation is highly desirable for high-density memory systems targeting the growing mobile market. This paper presents various challenges in engineering a ReRAM cell suitable for high-density applications such as material selection, programming algorithms, noise issues and scaling path.