Supercapacitors (SCs) are energy storage devices with high power density and robust charge/discharge life cycles. The high power density of these energy storage devices makes them attractive storage devices in conjunction with other reversible electrical energy storage devices such as batteries and conventional capacitors. The common SCs are made of nanostructured carbonous electrode materials, which are limited with their relatively lower operating window and specific energy densities. Nanostructured metal oxide based carbonous composites are widely explored to overcome carbonous SCs. Rare earth (RE) oxides such as Nd2O3, Y2O3, and Eu2O3 are used in conjunction with carbonous/conducting polymers matrix for high specific density and operating voltage supercapacitors. The high band gap of RE oxides assists in achieving higher operating voltage window. The article will review the current status of RE oxide based supercapacitors and their physical properties in conjunction with underlying physical principles. © 2020, Springer Nature Singapore Pte Ltd.