A nitrous oxide (N2O) removal catalyst composition for treating an exhaust stream of an internal combustion engine is provided, containing a platinum group metal (PGM) component on a metal oxide-based support, wherein the N2O removal catalyst composition is in a substantially reduced form, such that it has an oxygen deficiency of about 0.05 mmol oxygen atoms/g or greater, and wherein the N2O removal catalyst composition provides effective removal of at least a portion of N2O from the exhaust stream under lean conditions at a temperature of about 350° C. or lower. N2O removal catalytic articles, systems, and methods are also provided for removing at least a portion of N2O from an exhaust stream under lean, low temperature conditions.